The Wisconsin State Assembly approved a bill Thursday that would slash union rights for public workers. The vote comes a day after the state Senate used a legislative maneuver to pass the bill without the 14 Democratic senators who fled the state in an effort to block it.

The bill, proposed by Republican Gov. Scott Walker, is considered the most devastating blow to labor unions in many years and in the last three weeks has drawn thousands of union supporters to the state Capitol in protest. The measure passed the Assembly, 53 to 42. Republicans agreed to two hours of debate before calling a vote.

Before the vote, police briefly locked down the Capitol in Madison Thursday as thousands of protesters swarmed outside and members of the GOP-led State Assembly neared a final vote on a bill that would slash union rights for public workers.

The Assembly session was delayed when some Democratic representatives could not make it into the chamber as at least 100 protesters packed the hallway of the Capitol and pounded on drums.

Police carried out about 50 protesters, according to the Associated Press, and ordered a temporary lockdown while officers did a security review. The doors were opened just before 11:30 a.m., AP said.

Speaking during the session, Rep. David Cullen (D) said that he was turned away by police when he tried to enter the Capitol and “crawled through a window with one of the Republican members on the ground floor.”

Earlier Thursday, the Democratic senators who fled Wisconsin last month to try to stall a vote on the measure said they were preparing to return to the state capital and fight back against what one of them called “political thuggery in its worst form.”

State Sen. Robert Jauch said the Democrats are discussing ways to overturn the legislation.

After stripping the bill of fiscal measures that require a 20-member quorum for action, Senate Republicans abruptly passed the measure 18-1. Republican Sen. Dale Schultz cast the lone no vote. Analysts say the bill would cripple most of the state’s public employee unions.

“They acted more like a third coup than a democratic institution that has long been revered,” Jauch said in a telephone interview Thursday.

He said that because the vote was over, there was no reason for the senators to remain out of state. At least two might already be back in Wisconsin, and the rest were preparing to return, Jauch said, adding that he might return on Saturday.

Walker spoke during a Thursday news conference in Milwaukee shortly before the state Assembly was scheduled to take up the measure.

Walker said that he’ll sign the legislation “as quickly as I can legally,” AP said.

“The whole world is watching!” protesters shouted.

In statements Thursday, Assembly Minority Leader Peter Barca said: “Today citizens are being hauled from the lobby outside chambers, some media are allowed in while others are barricaded out, representatives and citizens are barred from the building … this is the atmosphere as we approach the start of floor session today. Republicans have made a mockery of democracy.”

Barca urged the protesters at the Capitol and across the state to keep demonstrations peaceful. “Wisconsin has been a model for peaceful demonstration around the world.... Please follow the law and be peaceful in your protests, whatever the outcome may be from the Assembly session.”

Jauch, the Democratic senator, declined to elaborate on discussions about what actions the Democrats would take when they returned but said they were considering “legal action.”

He added that the Democrats might offer resources to the recall petitions already circulating for the Republican senators who were involved in the vote.

“Their reckless behavior shows contempt for the citizens of Wisconsin, and it is now in the hands of citizens to take the necessary political action to recall Republican lawmakers,” Jauch said.

The White House reiterated its condemnation of the legislation on Thursday. President Obama “believes it is wrong to use those budget problems [of states across the country] to denigrate or vilify state employees, and he believes the actions taken last night violate the principles he laid out,” White House Press Secretary Jay Carney said in a press briefing.

Last month, Obama called the proposal “an assault on unions” when Gov. Scott Walker initially started pushing it, but had said little about it since then or about similar proposals from other Republican governors. Carney said Obama continued to view it as an “assault.”

The legislation, which the Republican-led Wisconsin Senate approved on Wednesday, would eliminate most collective bargaining for public employees in the state. It would also prevent unions from requiring members to pay dues and stop unions from collecting dues with payroll reductions, as well as require state workers to pay more for their health care and pensions.

The standoff in Wisconsin has gone on for three weeks, thrusting public employee unions into a deep crisis. States are grappling with record budget deficits, which some governors have tried to close by trimming what they call the generous benefits enjoyed by public employees.

The measure to curtail union power has been followed similarly in other states, including Ohio and Indiana.

The legislative maneuver used to pass the bill in Wisconsin was met with outrage by Democrats and their allies, and they vowed that Walker and state Senate Republicans would pay with their jobs.

“The vote does nothing to create jobs, does nothing to strengthen our state, and shows finally and utterly that this was never about anything but raw political power,” said Mike Tate, chairman of the Wisconsin Democratic Party. “We now put our total focus on recalling the eligible Republicans who voted for this bill. And we also begin counting the days remaining before Scott Walker is himself eligible for recall.”

Walker, however, appeared undaunted as he applauded the Senate’s action. In a statement, he said the state could not afford to be paralyzed any longer by a controversy that had caused Democratic senators to flee for Illinois and brought tens of thousands of protesters to the state Capitol.

“Senate Democrats have had three weeks to debate this bill and were offered repeated opportunities to come home, which they refused,” Walker said. “In order to move the state forward, I applaud the legislature’s action today to stand up to the status quo and take a step in the right direction to balance the budget and reform government.”

The bill would eliminate most collective bargaining for public employees across Wisconsin, while preventing unions from requiring members to pay dues, and stopping unions from collecting dues with payroll deductions.

Walker’s measure would also require state workers to pay more for their health care and pensions — something they had agreed to do.

Though Wisconsin’s budget problems are modest when compared with those of other states, Walker said the bill was necessary to ensure the state’s fiscal future.

Not only will it help him close a $137 million gap in the current budget, Walker has said, but it would help local governments deal with the huge cuts in state aid contemplated in his biennial budget proposal, without raising taxes. He said his approach will help improve the state’s business climate and create jobs.

Without unilateral power to divert more of state workers’ wages to pay for health care and pension benefits, Walker has said, state and local governments would have to lay off as many as 12,000 employees over the next two years. Last week, he notified unions that he would lay off as many as 1,500 state workers if his budget repair bill was not enacted.

Union leaders say the bill’s impact would be devastating to their organizations. But they also are calculating that Walker has gone too far. Activists have launched recall campaigns against eight Republican state senators, efforts they hope will culminate next year in a recall campaign directed at Walker.

GOP activists also are targeting some Democrats for recall. But polls show that though most people support reining in public employee benefits, they oppose stripping unions’ collective bargaining rights.

“By stripping out the fiscal items and leaving only the elimination of collective bargaining, the governor has exposed himself as a fraud,” said Jauch said Wednesday. “Tonight he has guaranteed that the people of the state of Wisconsin are going to stay engaged until this government changes.”

National Democratic activists are hoping that the battle in Wisconsin energizes their supporters and creates energy for them that carries into the 2012 presidential election.

“This has the potential of being a spark that builds a fire on the progressive side going into the presidential campaign,” said Robert Borosage, co-chairman of the Campaign for America’s Future, a liberal activist group.

The governor’s aggressive approach appears not to be playing well with Wisconsin voters, who elected him with 52 percent of the vote last fall.

A Rasmussen poll last week found that 57 percent of likely voters in Wisconsin disapprove of the job Walker is doing, while 43 percent approve.

The plan to pass the measure went into motion Wednesday, when state Sen. Scott Fitzgerald, leader of Wisconsin’s 19 Senate Republicans, called a conference committee of legislative leaders from both houses with just two hours’ notice.

As some onlookers shouted “shame, shame,” the committee passed the streamlined bill over the heated protests of Minority Leader Barca (D). “This is clearly a violation of the open meetings law,” said Barca of the meeting.

Barca said that state law requires 24-hour notice for public meetings, unless there is “good cause” not to provide it. But Republicans ignored his complaint, passing the measure out of the conference committee over his objections.

Speaking to reporters afterward, Barca called the maneuver “a continuation of a pattern of naked abuse of power” by Wisconsin Republicans. “They trample on democracy.”

He added that he was referring the action to the attorney general and was going to meet with fellow Democrats to seek other ways to stop the action. “This will not stand, that is one thing I will predict,” he said.

After Wednesday night’s vote, hundreds of noisy protesters were again gathered at the Capitol, witnesses said.

“I think you will see signatures being gathered on recall petitions at four times the rate they were yesterday,” Jauch said. “This is just outrageous behavior.”

Staff writers Peter Whoriskey and Perry Bacon Jr. contributed to this report.