It's getting harder to argue that stricter gun laws are needed when violent crime has fallen by 65 percent since 1993.
But the next president may well fill at least one Supreme Court seat, and the court is narrowly divided on gun control. An Obama appointee could be expected to be friendlier to gun controls than would a Romney nominee.
America's health care system is unsustainable. It's not one problem, but three: cost, quality and coverage.
The U.S. has world-class hospitals and doctors. But it spends far more than other advanced countries and people aren't much healthier. And in an aging society, there's no reliable system for long-term care.
Obama's expansion of coverage for the uninsured hits high gear in 2014. Obama keeps today's Medicare while trying to slow costs. He also extends Medicaid.
Romney would repeal Obama's health care law but hasn't spelled out what he'd do instead. On Medicare, he favors the option of a government payment to help future retirees get private coverage.
The risk of expanding coverage: Health costs consume a growing share of the stressed economy. The risk of not: Millions continue uninsured or saddled with heavy coverage costs as the population grows older.
An estimated 11.5 million illegal immigrants are living and often working in the United States. Figuring out what to do with them has confounded Washington for years.
Lax enforcement could mean more illegal immigrants competing with citizens and legal immigrants for jobs and some social services. A too-tight policy could mean farmers and others in industries that rely on the cheaper labor of illegal immigrants are left begging for workers, passing higher costs on to everyone else or going out of business.
Obama backed the DREAM Act, a failed bill that would have provided a path to legal status for many young illegal immigrants. In June, Obama decided to allow as many as 1.7 million of them to stay for up to two years. Romney has said he would veto the DREAM Act, though during the second presidential debate he said he supports a path to legal status for young illegal immigrants. He would honor any work permits issued under Obama's plan to delay deportations for many young illegal immigrants but wouldn't accept new applications for the programs.
The income gap between the rich and everyone else is getting larger, while middle incomes stagnate. That's raised concerns that the middle class isn't sharing in economic growth as it used to.
Obama would raise taxes on households earning more than $250,000 a year, plus set a minimum tax rate of 30 percent for those earning $1 million or more. He also wants to spend more on education, "a gateway to the middle class." Romney would cut taxes more broadly and says that will generate enough growth to raise all incomes.
Income inequality has risen for three decades and worsened since the recession ended. The Census Bureau found the highest-earning 20 percent earned 51.1 percent of all income last year. That was the biggest share on records dating to 1967. The share earned by households in the middle 20 percent fell to 14.3 percent, a record low.
Much of America's infrastructure — the interstate highway system, mass transit networks and more — is well-over half a century old and in need of serious repair and modernization. System breakdowns and bottlenecks are slowing commerce, at a cost to the economy and America's global competitiveness. The World Economic Forum put the U.S. 24th last year in the quality of its infrastructure, down from fifth in 2002.
The dilemma facing any president is how to maintain critical public works when budgets are crippled. Both candidates say infrastructure is important. The divide is over how to pay for it, and which projects.
Obama has favored stimulus-style spending and pushed for innovations like high-speed rail. Romney favors less federal involvement. He also shuns the idea that public-works spending is a good way to jumpstart the economy, saying decisions on projects should be based on need and potential returns.
With the Iraq war over and Afghanistan winding down, Iran is the most likely place for a new U.S. military conflict.
Obama says he'll prevent Iran from acquiring nuclear weapons. He hopes sanctions alongside negotiations can get Iran to halt uranium enrichment. But the strategy hasn't worked yet. Obama holds out the threat of military action as a last resort.
Romney accuses Obama of being weak on Iran. He says the U.S. needs to present a greater military threat. Yet he says sanctions are working and war should only be considered when all else fails.
Attacking Iran is no light matter. That is why neither candidate clearly calls for military action.
Tehran can disrupt global fuel supplies, hit U.S. allies in the Gulf or support proxies such as Hezbollah in acts of terrorism. It could also draw the U.S. into an unwanted new war in the Muslim world.
As concern intensifies over Iran's nuclear program and the rise of Islamist governments in the Middle East, America's top ally in the region, Israel, has become increasingly wary. Israel's security has been a U.S. foreign policy priority of both Democratic and Republican administrations since the Jewish state was created in 1948.
Although small, Israel has significant influence in Washington and presidents of both parties have pledged their commitment to its defense. And it's always a potential flashpoint in a region that the U.S. depends on for oil.
Obama has continued the strong support for Israel. Both American and Israeli officials say security cooperation is as strong as it has ever been. But the Obama administration has become embroiled in several very public spats with Benjamin Netanyahu's government.
Romney sharply criticizes Obama's policy on Israel. He's friendly with Netanyahu, visited Israel in July and vows unreserved U.S. support.
Unions have long been viewed as a way for workers to gain job protections, boost wages and benefits and live a middle-class life. But organized labor has been in a tailspin for decades, losing millions of members and the influence it once wielded in the workplace.
About 14.8 million Americans are members of labor unions. That's just 11.8 percent of the workforce — down from about a third of all workers in the 1950s.
The numbers have dropped as domestic manufacturing jobs go overseas and businesses take a tougher approach against union organizers.
Union leaders want Washington's help in making it easier to organize members and promote the use of union labor. They've had some success under Obama. But Romney says as president, he would reverse all of Obama's union-friendly executive orders. And he'd seek national right-to-work legislation prohibiting unions from collecting dues from nonmembers.
Missile technology is proliferating. It remains unclear how quickly foes like Iran and North Korea could develop a capability to reach the United States with missiles, but the U.S. says Iran is already able to hit allies in Europe.
The United States is spending nearly $10 billion a year on missile defense when military budgets are stretched. But the programs have yet to prove that they can reliably knock long-range missiles out of the sky.
The U.S. is deploying missile interceptors not only on home soil, but in Europe and Asia, drawing complaints from Russia and China. Moscow has said it will resist plans backed by both Obama and Romney. Romney has said he will not compromise with Russia on U.S. missile defense capabilities. And he opposes a missile-defense spending cut favored by Obama.
High unemployment and economic weakness have fueled fears that the U.S. is losing well-paid jobs to low-cost countries such as China. The decision by high-tech firms such as Apple to manufacture in China has raised concerns that higher-skilled jobs are also being lost.
Obama has proposed a variety of tax changes that he says will discourage outsourcing. Romney promises to make the nation more attractive for businesses to locate by cutting taxes and reducing regulations. The issue has arisen even as there are signs the outsourcing trend is slowing.
Wages are rising in China while wages and other costs are falling in the United States. That's eroding China's cost advantage. Obama and Romney hope to encourage more companies to keep jobs in the U.S. But it's unlikely that anywhere close to the 6 million manufacturing jobs lost from 2000 to 2010 will be regained.
A more racially and ethnically diverse population is rising in the U.S. and, perhaps within three decades, whites will no longer be the majority. That means shifts in political power, the risk of intensified racial tensions and also the opportunity to forge a multiracial society unlike anything in America's past.
Nearly half a century after the signing of the Civil Rights Act, America elected its first black president in 2008. Obama says that milestone changed attitudes on race, but he never thought his election would bring about a post-racial America. He's tread carefully on matters of race, in some minds too carefully.
Romney appears to favor the melting pot ideal more than the mosaic, envisioning a future in which Americans put aside differences grounded in race and ethnicity to stand as one people. But blacks and Latinos continue to see their interests better represented by Democrats.
Unless Congress acts, the trust funds that support Social Security are on pace to run out of money in 2033, triggering an automatic 25 percent cut in benefits that millions of older Americans rely on for most of their income.
That may seem far off. But the sooner Congress acts, the more time to phase in changes slowly.
Social Security could be preserved for generations with modest but politically difficult changes to benefits or taxes, or some of both.
Obama hasn't laid out a detailed plan for addressing Social Security. Romney proposes a gradual increase in the retirement age and, for future beneficiaries, slower growth in benefits for the wealthy.
But nothing will happen without White House leadership.
For millions of retired and disabled workers, Social Security is almost all they have to live on. Monthly retirement benefits are $1,237; average disability benefits, $1,111.
Supreme Court appointments:
With four justices in their 70s, odds are good that whoever wins in November will fill at least one Supreme Court seat. The next justice could dramatically alter the direction of a court split between conservatives and liberals.
One new face could mean a sea change in how millions get health care, shape gay rights and much more.
Obama already has put his stamp on the court by selecting liberal-leaning Justices Elena Kagan and Sonia Sotomayor, 50-somethings who could serve a quarter-century or more. Romney has promised to name justices in the mold of the court's conservatives.
Since the New Deal, Supreme Court decisions have made huge differences in American lives, from rulings to uphold Social Security, minimum wage laws and other Depression-era reforms to ringing endorsements of equal rights. Big decisions on health care, gun rights and abortion have turned on 5-4 votes.
Syria's conflict is the most violent to emerge from last year's Arab Spring. The fighting has escalated into a civil war that has killed more than 33,000 people in the last 20 months, according to activists.
Obama wants Syrian President Bashar Assad to leave power. But he won't use U.S. military force to make that happen.
Romney says "more assertive" U.S. tactics are needed. Yet in the final presidential debate, he ruled out U.S. military involvement for now.
The future of Arab democracy could be at stake. After dictatorships fell elsewhere, critics say Assad's government has resorted to torture and mass killings to retain power.
Assad has long helped Iran aid Hamas and Hezbollah, destabilizing Lebanon while threatening Israel's security and U.S. interests in the Middle East.
But extremists among the opposition, Assad's weapons of mass destruction and worries about Israel's border security have policymakers wary about deeper involvement.
Terrorism is not a top concern for voters this election, polls say. That will change if terrorists pull off anything on a large scale or if overseas attacks like the one in Libya keep happening.
Osama bin Laden is dead and there hasn't been a successful attack by al-Qaida-inspired extremists on U.S. soil since the deadly shooting rampage in Fort Hood, Texas, in 2009. But terrorism remains a reality, as seen in the Libyan attack that killed U.S. Ambassador Chris Stevens and three other Americans. The assault injected the issue of diplomatic security into the presidential campaign and renewed questions about the quality of U.S. intelligence.
Also a reality: the huge expense of homeland security more than a decade after 9/11, the cost to privacy from surveillance in the U.S. and the toll in innocent lives from U.S. drone attacks that have killed known and suspected terrorists abroad.
Almost every U.S. taxpayer faces a significant tax increase next year, unless Congress and the White House agree on a plan to extend a huge collection of tax cuts expiring at the end of the year.
And there's a huge debate over how to overhaul the tax code to make it simpler, with lower rates balanced by fewer deductions.
Obama wants to extend Bush-era tax cuts again, but only for individuals making less than $200,000 and married couples making less than $250,000.
Romney wants to extend all those tax cuts and enact new ones, dropping all income tax rates by 20 percent. Romney says he would pay for that by eliminating or reducing tax credits, deductions and exemptions. But he won't say which ones would go.
Most lawmakers want a simpler tax code, but millions count on the mortgage interest deduction, child tax credit and more, making progress all but impossible.
Wall Street regulation:
The debate over banking rules is, at its core, a dispute about how to prevent another economic cataclysm.
The financial crisis that peaked in 2008 touched off a global economic slowdown. Four years later, the recovery remains painfully slow.
After the crisis, Congress passed a sprawling overhaul of banking rules and oversight. The law gives regulators new tools to shutter banks without resorting to emergency bailouts. It restricts risky lending and establishes a new agency to protect consumers from misleading marketing and other traps.
The new rules also boost companies' costs, according to Romney and many in the business community. Romney believes the law is prolonging the nation's economic agony by making it harder for companies to invest and grow. He has pledged to repeal it. Obama fought for and supports the law.
Associated Press writers Nancy Benac, David Crary, Tom Raum, Seth Borenstein, Robert Burns, Jack Gillum, Paul Wiseman, Carole Feldman, Mark Sherman, Matthew Pennington, Bradley Klapper, Ricardo Alonso-Zaldivar, Daniel Wagner, Stephen Ohlemacher, Alicia A. Caldwell, Christopher S. Rugaber, Jason Keyser, Sam Hananel, Desmond Butler, Richard Lardner, Tom Krisher, Jesse Washington, Matthew Daly, Matthew Lee, Suzanne Gamboa and Cal Woodward contributed to this report.
EDITOR'S NOTE _ A look at issues at stake in the election and their impact on people