THE AMBUSH IN MADISON…. Wisconsin Republicans had given their word that they would not move on Gov. Scott Walker’s (R) union-busting bill without Democrats’ participation. Wisconsin Republicans also assured the public that stripping workers of collective-bargaining rights was entirely about the state’s finances, not politics.

Last night, however, those same GOP officials launched an ambush, reversing course on their previous promises and ramming through an unjust, unpopular anti-worker measure.

The bitter political standoff in Wisconsin over Gov. Scott Walker’s bid to sharply curtail collective bargaining for public-sector workers ended abruptly Wednesday night as Republican colleagues in the State Senate successfully maneuvered to adopt a bill doing just that.

After a three-week stalemate, Republican senators pushed the measure through in less than half an hour even as the Senate’s Democrats remained many miles away, trying to block the vote. Democrats in the State Assembly complained bitterly, and protesters, who had spent many days at the Capitol, continued their chants and jeers.

The Republicans control the Senate but had been blocked from voting on the issue after Senate Democrats left the state last month to prevent a quorum. But the Republicans used a procedural maneuver Wednesday to force the collective bargaining measure through: they removed elements of Governor Walker’s bill that were technically related to appropriating funds, thus lifting a requirement that 20 senators be present for a vote. In the end, the Senate’s 19 Republicans approved the measure, 18 to 1, without any debate on the floor or a single Democrat in the room.

To make this possible, the GOP had to argue that the measures related to collective bargaining had nothing to do with fiscal considerations, effectively making a liar out of Walker and his allies. Of course, for Republicans, it was a worthy trade off — they traded their integrity and credibility for a bill to gut Wisconsin’s public-sector unions. To far-right officials, it was a sacrifice they were happy to make.

The proposal now goes to the State Assembly, which already passed the measure once, and where the result is a foregone conclusion.

The road ahead is uncertain. The measure will become state law fairly soon, but there’s likely to be a court challenge — last night’s stunt, among other things, may have violated Wisconsin’s open meetings requirements — and there’s been a fair amount of talk of a general strike.

But while those plans are considered, it’s worth appreciating the larger context. The political environment in and around Madison was already noxious as the debate over the governor’s plan intensified. Last night’s gambit only served to make the air significantly more toxic, enraging working families and their Democratic allies. Indeed, if the GOP were sweating over Democratic recall efforts before, Republicans have to realize they just put their majority in serious jeopardy.

If pushing the union-busting bill was the equivalent of poking the hornets’ nest, ramming it through this way was the equivalent of beating the hornets’ nest with a tire-iron and then daring the hornets to do something about it.

Walker and the GOP had a chance to accept a very favorable compromise. If the recall efforts are successful, they may soon wonder why they rejected a good deal.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.