MADISON - The leader of the state Assembly apologized Monday for calling fellow Republican senators "terrorists" after they held up the state budget with veto demands.

Assembly Speaker Robin Vos (R-Rochester) issued the apology after a chorus of criticism from other GOP leaders, but his statement continued to refer to the conservative senators as "rogue holdouts."

The episode illustrates how polarized the state GOP remains after last month's budget showdown and how conservatives are increasingly ascendant in the state Capitol.

"As speaker, I have (striven) to increase the civility within the Legislature. I now regret using the word terrorist because it goes against the guidelines I’ve set for our chamber, and myself. For that, I apologize," Vos said.

The senators didn't take kindly to the comments. One of them — Sen. Steve Nass (R-Whitewater) — noted that he had served in the Wisconsin Air National Guard.

"It is beyond outrageous for anyone, especially a person serving as speaker of the Wisconsin state Assembly, to label as a ‘terrorist’ another person for simple public policy disagreements," Nass said in a statement. "Worse yet, when given the opportunity in the interview to retract or recalibrate such a reprehensible statement, Speaker Vos firmly reiterated it."

Beyond the vetoes, Vos has a litany of budget complaints about conservatives, including their successful efforts to block an increase in the gas tax to pay for roads. Speaking with Mike Gousha of WISN-TV, Vos vented over the weekend, saying the veto talks between the holdout senators and Gov. Scott Walker amounted to obstructionism.

“Frankly, I wish Governor Walker had not negotiated with terrorists," Vos said on the Sunday program.

“You’re calling them rogue senators and terrorists?” Gousha responded.

“That’s what they are!” said Vos.

That drew criticism from Walker, Senate Majority Leader Scott Fitzgerald (R-Juneau) and Americans for Prosperity Wisconsin, the group backed by the brothers Charles and David Koch, the conservative billionaires.

"It’s unacceptable the word (terrorists) was used to describe good public servants at a time when our men and women in uniform are fighting terrorism around the world," Walker spokesman Tom Evenson said.

Another of the holdout senators, Sen. Duey Stroebel (R-Saukville), called the Vos comments the "type of hyperbolic rhetoric Wisconsinites are tired of hearing."

The budget was delayed for nearly three months because Walker and his fellow Republicans who control the Legislature could not agree on taxes and transportation funding. When they, at last, reached a deal that passed the Assembly, three conservative GOP senators — Stroebel, Nass and Chris Kapenga of Delafield — refused to let it pass in their house without changes.

Vos refused to make more changes in the Assembly, so the holdout senators turned to Walker, whose powerful veto pen offered them another potential solution. They essentially negotiated to give their votes in exchange for the governor's vetoes.

Those vetoes speeded up the repeal of a minimum wage for those working on public infrastructure projects; put tighter limits on when schools could hold referendums; and nixed a proposed expansion of a little-known, quasi-public entity that has issued billions of dollars in debt.

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POLITIFACT WISCONSIN:One Wisconsin GOP leader calling fellow Republicans 'terrorists'

Liberals have also criticized those budget negotiations, with some questioning whether Walker and the senators went too far in their deal-making.

But Fitzgerald said Vos should apologize for his statements, calling them "beyond inappropriate."

"Negotiating vetoes is as much a part of the budget process as anything else, and the speaker's comments demonstrate a weak grasp on the events that transpired in the hours before the budget was passed on the Senate floor," Fitzgerald said in a statement.

For his part, Vos questioned whether GOP lawmakers will have to "run everything past a few rogue holdouts before committees take" votes.

"If the governor has to negotiate every initiative with more than 80 individual legislators, nothing will get accomplished," Vos said in a statement.

The speaker has already clashed with Walker himself over the way the budget ended in a series of previously reported texts.

“I won’t forget this,” Vos texted to Walker after the governor announced his vetoes.

“Very disappointed in the way I've been treated ... not even the courtesy of a phone call before you took out things that were important to me,” Vos wrote.

Senate Minority Leader Jennifer Shilling (D-La Crosse) said in a statement that Republicans should "end the name calling" and focus on issues that voters value.

"Labeling colleagues as terrorists won’t restore school funding, fix our crumbling roads or protect access to health care for vulnerable families," Shilling said.