Republicans picked a silly fight over START, and they lost badly.
The Senate seems on its way to ratifying the New START on nuclear arms, an achievement that looked unlikely to say the least just a few weeks ago.
If a Republican were president, the accord would have excited no controversy and at most a handful of diehard nays. As even most of its critics conceded, the treaty's text contains nothing objectionable in substance.
There were two kinds of opponents in this debate. The first had concerns that President Barack Obama would use the treaty as an excuse to ease up on missile defense and the programs to maintain the nuclear arsenal. In recent weeks, Obama and his team did as much to allay these concerns as any hawk could have hoped—and more than many doves preferred.
So that left the second kind of opponent: those who simply wanted to deny Obama any kind of victory. The latter motive was clearly dominant in this debate.
The task of Obama and the Democratic floor managers, Sens. Harry Reid and John Kerry, was to convince enough Republicans to view the issue not as political gamesmanship but as an urgent matter of national security. Hence their rallying of every retired general, former defense secretary, and other security specialist—Republican and Democrat—that anyone had ever heard of. (At one point, Sen. Susan Collins, R-Maine, said she might vote for the treaty if former President George H.W. Bush endorsed it. A few days later, Bush released a statement doing just that.)
The amazing thing is, Obama and the Democrats pulled it off. Perhaps it was too obvious that the treaty's opponents were able to muster no outside officers or experts to their side, except John Bolton, who has never met a disarmament treaty he liked and who, faced with this treaty, had to dissemble even more blatantly than usual to make his case.
And so the Republican leadership made this a purely political battle and—fresh off what had seemed a triumphant election season—suffered an astonishingly egregious defeat.
It is extremely doubtful, for instance, that the Obama administration will ever again bargain over national-security issues with Sen. Jon Kyl, R-Ariz., the minority whip.
For reasons that nobody can quite explain, Kyl had managed in the past few years to cut a profile as the "go-to" Republican on all matters nuclear. The conventional wisdom was that if Kyl endorsed the treaty, it would pass; if he didn't, it wouldn't.
And so, the White House and the Pentagon sent high-level emissaries to Kyl's lair during the Senate's recess to negotiate a deal, offering, among other enticements, an extra $4 billion, on top of the $80 billion already committed over the next decade, to "modernize" the nuclear-weapons infrastructure.
Kyl took the goodies but came out against the treaty anyway. So Obama and his aides did something no legislative powerhouse should ever let happen—they went around him, treating him as just another senator, and they won.
Kyl limps away from this face-off gravely wounded—a leader unable to deliver either on his promises or on his threats.
Sen. Mitch McConnell, the minority leader, shot himself in the foot, too, coming out against the treaty only in the last couple days—thus making the Republican yea votes seem like a rebellion within a rank-and-file that, until now, has been remarkably disciplined.
An astonishing 11 Republicans broke ranks to vote for cloture and thus end the debate—a measure approved by 67 senators (enough to ratify the treaty when that vote takes place, probably Wednesday) and rejected by only 28.
It would go too far to interpret this vote as a pivot in the political contests to come. Just because Obama was able to split off nearly a dozen Republicans (instead of the usual one or two, at most) on a truly major political issue doesn't mean he'll be able to do the same on future votes about taxes, stimulus packages, energy programs, or even disarmament treaties.
Still, in the game of political perceptions, it's the Republicans who appear to be "reeling" now.
Fred Kaplan is Slate's "War Stories" columnist and author of the book, The Insurgents: David Petraeus and the Plot to Change the American Way of War. He can be reached at firstname.lastname@example.org. Follow him on Twitter.
Photograph of Mitch McConnell by Olivier Douliery-Pool/Getty Images.