For Moon, aggressive engagement isn't a reward for North Korean nuclear movement; it's the means to transforming the relationship so that "North Korea has an economic stake in a more moderate foreign policy and eventually has even an economic stake in denuclearization," said John Delury, a North Korea analyst at Seoul's Yonsei University.
Moon's candidacy has some in Washington worried about the return of the tension and anti-U.S. feelings that marked Roh's term — that "the ghosts of the anti-Americanism of the South Korean left will rise again," according to Delury.
The North's rocket launch was magnified because of its timing. Obama will be inaugurated in January to his second term, Japan and South Korea both have national elections this month, and China has just formed a new leadership. But the test is probably not going to "blunt South Korea's desire for renewed inter-Korean dialogue as a necessary step toward stabilizing peninsular relations," Scott Snyder, a Koreas specialist for the Council on Foreign Relations, wrote recently.
The Obama administration has consistently emphasized its solidarity with Seoul, and that rhetoric is unlikely to change, whoever is elected.
A rocket launch could actually "solve any alliance split problems" between Washington and either of the South Korean candidates by forcing a more unified stance, said Victor Cha, a former senior Asia adviser in President George W. Bush's administration.
Washington could also be willing to give either Park or Moon some leeway in reaching out to North Korea if it leads to movement on nuclear disarmament, the issue the United States cares most about. During a November visit to Myanmar, Obama said a decision by North Korea to give up its nuclear aspirations would result in "an extended hand" from the United States.
"A more flexible policy from Seoul also gives the Obama administration more political cover to try another overture toward the North," said Ralph Cossa, president of Pacific Forum CSIS, a Hawaii-based think tank.
Much will come down to the way North Korea treats the new South Korean leader. Pyongyang may expect, for instance, Moon to deliver everything his liberal predecessors promised, something seen as impossible in the current political environment. Pyongyang could also dismiss Park's attempts at engagement, dooming talks before they begin. North Korean media routinely criticize Park's North Korea policy as insincere and confrontational.
North Korea considers the United States, against which it fought during the 1950-53 Korean War, a major enemy. Seoul, on the other hand, is labeled a puppet of Washington, which has more than 28,000 soldiers stationed in South Korea.
"At the end of the day," Cossa said, "it will be the North's willingness, or not, to treat the South as a sovereign equal that will make meaningful dialogue possible, regardless of who is elected."
Associated Press writer Hyung-jin Kim contributed to this report.