A day after the biggest primary night of the election season, Sens. Hillary Rodham Clinton (D-N.Y.) and Barack Obama (D-Ill.) had a brief but warm interaction on the Senate floor during a cliffhanger vote over a Democratic economic stimulus package.

The two largely avoided eye contact during the vote, even as they stood feet away from each other and huddled with senators who have endorsed their respective campaigns.

With a smile on his face, Obama shook hands with Sen. Tim Johnson (D-S.D.), a supporter, and then approached the group speaking with Clinton.

Their minute-long conversation was inaudible to the on-looking press corps until Clinton blurted out: “I had a big sigh of relief when he endorsed you.” Letting out a big chuckle, her comments were clearly audible in the press gallery.

Massachusetts was one of the eight states Clinton won during the Super Tuesday primary night, even though Kennedy, Sen. John Kerry (D-Mass.) and Gov. Deval Patrick had all endorsed Obama.

The interaction differs from last time the two candidates were in the Senate, during the State of the Union on Jan. 28. Obama and Clinton did not shake hands before or after the president’s speech that night.

Since then, the two have sought to portray Democrats as more united than Republican candidates, and Obama has gone to lengths to explain his admiration and friendship for Clinton.

After their encounter Wednesday, Obama spoke to Kerry privately and Clinton continued her conversation with  Feinstein.

Clinton later sat down for a lengthy chat with Sen. Jim Webb (Va.), the freshman Democrat and former Navy Secretary seen as a possible vice presidential choice. Webb has not endorsed either candidate.

The two were sitting behind Kennedy as he chatted with Senate Majority Whip Dick Durbin (D-Ill.), who is playing a major role in his homestate senator’s presidential campaign. Clinton and Durbin did not appear to interact.

Later, Obama headed over to the Republican side. There he had an animated conversation with Sens. Bob Bennett (R-Utah), a supporter of Republican Mitt Romney, and Sen. Bob Corker (R-Tenn.), who has not endorsed any of the current GOP candidates. Clinton mainly sat on the Democratic side.

Despite their return from the campaign trail, Democrats fell one vote shy of the 60 votes they needed to bring forward their preferred economic stimulus bill.

Sen. John McCain (Ariz.), the frontrunner for the Republican nomination, missed the vote.