This time it was the Democratic leader who urged calm. “The recent effort to avert the fiscal cliff was an example of both the divisions and the collaborations that will mark a moment in history – and it was a moment in history,” said Senate Majority Leader Harry Reid of Nevada.

The new Congress began with slightly more Democrats than its predecessor had. The party now controls 55 Senate seats, up two from the last Congress. In the House, Republicans have a 233 to 200 majority, down eight seats.

The makeup is slightly different. For the first time, the House Democratic caucus doesn’t have a majority of white men. Eighteen percent of House members and 20 percent of senators are women. Nineteen percent of House members and 6 percent of Senators are minorities.

Senators who won election or re-election were called in alphabetical small groups and sworn into office by Biden, who’s the president of the Senate. Sen. Tim Scott of South Carolina made history as the first African-American senator from the South since Reconstruction and the first African-American Republican senator since Ed Brooke of Massachusetts left in 1979.

Sen. Tammy Baldwin, a Wisconsin Democrat who defeated popular former Republican Gov. Tommy Thompson for the Senate seat vacated by Democrat Herb Kohl, became the first openly gay senator.

Reid put off any first-day bickering by the new Senate class when he postponed action on revamping debate rules. The proposal, by Sens. Tom Udall, D-N.M, Jeff Merkley, D-Ore., and Tom Harkin, D-Iowa, has drawn fire from Republicans as well as a few Democrats.

Among other things, the measure would require senators to speak on the floor to sustain extended debate, and would cut the time after debate limits have been imposed from the current 30 hours to two hours.

The House adopted a measure that will, among other things, allow it to keep up its legal bid to defend the Defense of Marriage Act, which defines marriage as between a man and a woman, and to require Attorney General Eric Holder to comply with subpoenas related to the Fast and Furious gun-walking operation.

The Obama administration said two years ago that it would no longer defend the Defense of Marriage Act, but a House Republican group is doing so.