Both the current House and Senate versions also award a new congressional seat to Utah, a heavily Republican state that barely missed getting one after the last census. In the short term, the new Utah seat would probably balance the impact of a House member with full voting rights from the mostly Democratic District of Columbia.

The legislation would also expand the size of the House from 435 members to 437. But while the Senate version would require the drawing of a fourth congressional district for Utah, the House would create an at-large district in that state.

“It [the at-large seat] is clearly not constitutional,” Hatch said. “I don’t think this will pass if it’s in there.”

The Senate measure includes language clarifying that while Utah would get the additional seat at the start of the 112th Congress, the additional seat for the 113th Congress and beyond would be awarded based on the 2010 census population figures.

Both versions would increase the size of the Electoral College to 539 members.

The most contentious debate Thursday was over the amendment dealing with the District’s gun laws.

Majority Whip Richard J. Durbin of Illinois challenged the amendment, saying it is “one of the most extreme pieces of legislation on the issue of guns” that he’d seen.

“If successful it will be the first new step in a march to remove all common-sense gun regulations all over this land,” Sen. Dianne Feinstein . D-Calif., argued.

Ensign dismissed the criticism.

“Will law-abiding citizens be able to protect themselves in their own homes? That is what this amendment is attempting to do, to say to citizens living in the District of Columbia, we will protect your rights,” Ensign said.

Bill supporters decried the introduction of non-germane amendments for politically difficult issues. But Zherka said the amendment didn’t take away “from the historic moment.”

Additional Amendments

The chamber spent Thursday voting on numerous amendments, some of which were aimed at derailing the measure.

Minority Whip Jon Kyl , R-Ariz., offered the amendment to return all non-federal land in the District back to Maryland, provided that Maryland agrees to take it back and that the provision in the 23rd Amendment giving the District three votes in the Electoral College is repealed. It was rejected, 30-67.

Jim DeMint , R-S.C. offered an amendment that would prevent the Federal Communications Commission from reinstating the so-called “fairness doctrine,” a defunct rule that required broadcasters to present opposing points of view on controversial issues. Obama has said he opposes reviving that policy. It was adopted, 87-11.

Durbin had a companion amendment that would promote diversity in communication media ownership as well as ensure that broadcast station licenses were used in the public interest. The amendment does not deal with the doctrine. It was adopted, 57-41.

This week was the first time since 1978 that the full Senate had debated giving a full House voting representative to the District. That year, Congress cleared a joint resolution for a constitutional amendment that would have treated the District as a state for congressional representational purposes.

However, after a seven-year period for ratification, only 16 of the required 38 states had voted yes for the amendment.

Del. Eleanor Holmes Norton , who has represented the District of Columbia in Congress for 18 years, said after the vote: “Winning the Senate is like winning the lottery.”

She recalled that her great-grandfather Richard Holmes was a slave who walked off a Virginia plantation and settled in the District. “For me, this is a historic occasion because there are so many people who gave so much who cannot be here today.”

Kathleen Hunter contributed to this story.