CNN

Lieberman addressed the Republican National Convention on Tuesday night.

WASHINGTON (CNN) - Sen. Joe Lieberman’s speech before the Republican National Convention Tuesday night could cost Lieberman the chairmanship of a key Senate committee, a top Senate Democratic aide told CNN.

During the speech, the Connecticut senator praised GOP presidential candidate Sen. John McCain and criticizing Democratic nominee Sen. Barack Obama.

"The Democratic Caucus will reassess the situation with Sen. Lieberman after the election,” Jim Manley, a spokesman for Senate Majority Leader Harry Reid, said Wednesday.

Lieberman, the Democratic nominee for vice president in 2000, now calls himself an “independent Democrat,” but he remains a member of the Senate Democratic Caucus which allows him to head the Homeland Security and Governmental Affairs Committee.

Democrats have grumbled for months about Lieberman’s outspoken support of McCain and both Reid and Obama have warned Lieberman to curb his public criticism of Obama.

“What we saw last night was a culmination of provocative efforts in recent months,” said a Democratic leadership aide.

Democrats, who with Lieberman’s support control the chamber by a narrow 51-49 margin, are unlikely to go a step further and boot Lieberman from their caucus although the Democratic leadership aide didn’t rule out that punitive step if Democrats pick up several seats in November.