Democrats have been helped to a lesser extent by the Democratic Legislative Campaign Committee, which has sent mailers and run radio ads around the state.
Acknowledging defeat in the state Senate, Democrats said they had faced an uphill battle in the election and called on both parties to work together in the Legislature.
"The time for arguing is over," said Candace Martin, a spokeswoman for the Arkansas Democratic Party. "It's now time to continue moving the state in the right direction, regardless of political party."
Republicans have not had a majority in the state Legislature since 1874, a run of 138 years, and Arkansas is the only former Confederate state where Democrats control the Legislature and the governor's office.
The GOP claimed the state's only Democrat-held congressional seat in south Arkansas. Republican Tom Cotton, an Army veteran and former management consultant, defeated Democrat state Sen. Gene Jeffress in the race for retiring U.S. Rep. Mike Ross's 4th District seat.
Cotton told The Associated Press his victory showed "that Arkansans are ready for a new generation of conservative leaders, leaders who will stand on those principles of limited government and natural rights and free enterprise."
Republican U.S. Rep. Rick Crawford defeated Democratic challenger Scott Ellington in their race for the 1st Congressional District in east Arkansas. Ellington helped negotiate the deal last year that freed three men who were convicted as teenagers in the 1993 murders of three Cub Scouts in West Memphis. Crawford, who was elected in 2010 partly on a pledge to oppose any tax increases, proposed hiking taxes on millionaires earlier this year in exchange for a balanced budget amendment.
"This is a pretty strong statement for Arkansas that Arkansans want to see conservative representation and conservative leadership not only in Washington but I think around the country we're seeing that," Crawford told the AP.
Republican Rep. Steve Womack, who did not face any major party opposition after his Democratic challenger dropped his bid over questions about his military record, won re-election to his northwest Arkansas seat.
Voters approved a half-cent sales tax to pay for highway improvements, but rejected a new funding mechanism for local development projects. With about 91 percent of precincts reporting unofficial results, 51.6 percent of voters opposed a measure that would make Arkansas the first southern state to legalize medical marijuana.