The officials spoke Thursday on the condition of anonymity because Mehlman had not yet made his intentions public.
Brian Jones, an RNC spokesman, declined to comment beyond saying that an announcement about Mehlman's future with the party would be made in the days ahead.
Democrats won control of the House and Senate on Tuesday by capitalizing on voter frustration with President George W. Bush, the war in Iraq and the scandal-scarred Congress. Democrats also took a majority of governors' posts and gained a decisive edge in state legislatures.
During his tenure, Mehlman, 40, traveled extensively to promote the Republican agenda. When he became chairman in January 2005, he said he hoped to tighten the Republicans' grip on power in Washington.
"Nothing is permanent in politics," he said then. "The goal is how do you — both in the short term and the long term — do things to make it sustainable?"
Mehlman also said then that he hoped to expand the Republican base and help Bush enact his agenda.
Last year, Mehlman told members of the National Association for the Advancement of Colored People that the Republican Party was wrong for ignoring the black vote for decades and said he hoped the groups could restore their historic bond.
"Some Republicans gave up on winning the African-American vote, looking the other way or trying to benefit politically from racial polarization," Mehlman said at the NAACP convention. "I come here as Republican chairman to tell you we were wrong."
A protégé of Bush's top political adviser, Karl Rove, Mehlman became RNC chairman after managing Bush's re-election campaign in 2004, when the president won re-election and Republicans expanded their majorities in the House and the Senate.
Before that campaign, he served as White House political director under Rove. In 2000, he served as national field director for Bush's first presidential campaign, charged with coordinating the efforts of Republican leaders in every state.
Previous to that, he worked on Capitol Hill and practiced environmental law in Washington.