Wednesday was not a good day for Senator Mitch McConnell's single-minded project to make Barack Obama a one-term president. Over the minority leader's objections, 13 Republicans joined every Democratic senator to ratify the New Start nuclear arms treaty with Russia, reducing the size of the countries' nuclear stockpiles and making the world a safer place. The 71-to-26 vote was the capstone to what now shapes up to be a remarkably successful legislative agenda for President Obama's first two years.

Earlier in the day, the president signed a bill allowing the repeal of the military's ban on open service by gay, lesbian and bisexual soldiers — a bill passed with the assistance of 23 Congressional Republicans, again over the objections of Mr. McConnell.

And the Senate unanimously approved a bill to pay for the medical care of workers who cleaned up ground zero after the attacks on Sept. 11, 2001, coming to its senses after Mr. McConnell and other Republicans blocked the bill 13 days earlier, causing a national uproar.

(Unfortunately, the bill was scaled back substantially by the demands of a few holdout senators who thought it was too generous, though it added nothing to the deficit. The bill was later approved by the House.)

These deeply gratifying developments hardly spell the end of partisanship, which is likely to return with a vengeance in the next Congress. But they do suggest that many Republicans are willing to reject Mr. McConnell's particularly noxious version, under which any bill, no matter how beneficial for the country, can be blown up if it could be seen as a victory for President Obama. On Tuesday, to pick one shabby example, he made a thoroughly underhanded attempt to sabotage the repeal of "don't ask, don't tell" when he thought no one was looking.

In a more rational world, of course, the ratification of New Start could have been done by unanimous consent. Though the treaty is vital, it makes relatively modest reductions in the nuclear stockpile and continues the inspection regime employed by Democratic and Republican presidents going back to Ronald Reagan. If the same document had been signed by a Republican president, it would have been approved months ago.

In the obstructionist climate of the 111th Congress, the ratification could be done only in the last hours. Mr. McConnell and his allies, notably Jon Kyl of Arizona, put up a series of specious arguments to delay it, mostly centering around a fiction: that the treaty would prevent the United States from erecting a missile defense system. Their efforts backfired, making Mr. Obama's victory ring more loudly that it should have.

Thirteen Republicans wouldn't buy that nonsense, and others saw the wisdom in letting all Americans serve their country honestly and openly. Those defeats and others infuriated the party's dead-enders. "Harry Reid has eaten our lunch," complained Senator Lindsey Graham of South Carolina, who voted against both measures, referring to the majority leader.

There were disappointments in the lame-duck session, and Mr. Obama said at a news conference that the biggest was probably the Republicans' killing of the Dream Act, which would have given the children of illegal immigrants a chance at being legal if they serve in the military or attend college. The failure of the Senate to pass a spending bill for the current fiscal year means that the budget fights in the next term will be deeper and longer, and potentially more destructive to the economy.

Mr. McConnell won those fights. But to be repudiated on the treaty and on "don't ask" by so many members of his own caucus clearly stung, and turned him into a very sore loser. On Tuesday, Mr. McConnell tried to sneak an amendment into the defense authorization bill that would require the approval of each military service chief before "don't ask, don't tell" could be repealed. Given the continuing reservations of the Marine Corps, that could have stalled progress indefinitely. But Joseph Lieberman objected to the amendment, and it was defused.

Next term, there will be many more Republicans in Congress spoiling for a fight, and the White House will have to be far more pugnacious and adept to preserve its priorities and avoid trickery and extortion. But this week's examples of Democrats and Republicans coming together for a common purpose will not soon be forgotten. As the president said on Wednesday, if that continues, "we are not doomed to endless gridlock."