The stepped-up tactic ordered by the Republican head of the Senate came amid reports that at least a few of the missing senators were returning home at night before rejoining their colleagues in Illinois.
Meanwhile, the state Assembly appeared close to voting on the union-rights bill after more than two straight days of filibustering.
Democrats agreed before dawn Thursday to limit the remaining number of amendments they offer and the time they devote to each one. That could bring a vote later in the day on the measure Gov. Scott Walker insists is necessary to ease the state's budget woes and avoid mass layoffs.
"We will strongly make our points, but understand you are limiting the voice of the public as you do this," said Democratic state Rep. Mark Pocan of Madison. "You can't dictate democracy. You are limiting the people's voice with this agreement this morning."
The marathon session in the Assembly was grand political theater, with exhausted lawmakers limping around the chamber, rubbing their eyes and yawning as Wednesday night dragged into Thursday.
Around midnight, Rep. Dean Kaufert, a Republican from Neenah, accused Democrats of putting on a show for the protesters. Democrats leapt up and started shouting.
"I'm sorry if democracy is a little inconvenient, and you had to stay up two nights in a row," Pocan said. "Is this inconvenient? Hell, yeah, it's inconvenient! But we're going to be heard!"
Democrats, who are in the minority, don't have the votes to stop the bill once the vote occurs.
But even after the bill passes the Assembly, it cannot become law until it also passes the Senate, where action has been stymied by the absence of the Democrats. At least one of them needs to be there in order for Republicans to take up the bill since the GOP is one seat short of having a quorum.
The Senate convened at 7 a.m. Thursday just long enough to take a roll call, which allows for the sergeant at arms staff to go to missing lawmakers' homes with police.
Troopers went to multiple homes but left after finding no one home, said Sergeant at Arms Ted Blazel.
Wisconsin law does not allow police to arrest the lawmakers, but Fitzgerald said he hoped the show of authority would pressure them to return. He would not say how many Democrats were being targeted, but said it was more than one.
"Every night we hear about some that are coming back home," Fitzgerald said. Whether to send police out again is a day-by-day decision, he said.
Democratic Sen. Jon Erpenbach, who was in the Chicago area, said all 14 senators remained outside of Wisconsin on Thursday morning and would not return until Republican Gov. Scott Walker was willing to compromise.
"It's not so much the Democrats holding things up," Erpenbach said. "It's really a matter of Gov. Walker holding things up."
Walker's spokesman Cullen Werwie issued a statement praising the Assembly for moving toward a vote and renewing his call for Senate Democrats to come back.
Walker has repeatedly warned that if the budget bill does not pass by Friday, the state will miss a deadline to refinance $165 million of debt and will be forced to start issuing layoff notices next week.
While Walker is trying to increase the pressure to act, the deadlines may not be quite as strict as he says.
The nonpartisan Legislative Fiscal Bureau said in a memo sent to lawmakers earlier this week that the debt refinancing could be pushed as late as Tuesday in order to achieve the savings Walker is seeking.
The governor is trying to balance a projected $137 million budget shortfall by July.
Based on a similar refinancing in 2004, about two weeks are needed after the bill becomes law to complete the refinancing, which means if the bill is adopted by the middle of next week, the state can still meet a March 16 deadline, the Fiscal Bureau said.
Walker has suggested the deadline is actually Friday in order to pressure lawmakers to act on the bill, which has drawn tens of thousands of protesters to the Capitol. The rallies reached a high of 68,000 people on Feb. 19 and hundreds have stayed overnight.
Fitzgerald said the real deadline is "up in the air."
"Everything's in place, it's ready to go," he said. "It just needs to be finalized."
Werwie said the governor was "uncomfortable with the time frame for refinancing if the bill passes after Friday."
Walker also threatened to start sending layoff notices to up to 1,500 state workers next week if the bill isn't passed, arguing he has no other choice to deal with the shortfall. He has not said who would be targeted.
School districts have already started sending out preliminary layoff notices in case they are needed later.