ST. PAUL — The head of the Minnesota Republican Party called him “exactly the kind of career politician that has plagued politics for far too long” and accused “union bosses” of trying to buy his election.

GOP Chairman Pat Shortridge wasn’t talking about a Democrat — he was referring to Rep. Steve Smith, the senior Republican in the Minnesota House, a 22-year legislative veteran who could be forced out by a conservative newcomer in Tuesday’s primary. Republican House Speaker Kurt Zellers, too, is supporting challenger Cindy Pugh, saying the Tea Party activist “isn’t someone who is going to let a special interest push her around.”

The race in the Lake Minnetonka area is one of three Republican primaries where incumbent legislators are imperiled by challenges from the right. Pugh, Mound City Councilor Dave Osmek and auto mechanic Bruce Schwichtenberg hope to tap into discontent among Republicans impatient with the pace of change under current GOP majorities in the Legislature. Incumbent Democrats haven’t faced such strong primary challenges from within their own party this year.

The primary contests will set the field for a big November fight to control the Legislature. Republicans can lose at most three Senate seats and five House seats to stay in charge of both chambers. Democrats controlled the Legislature until two years ago, when they lost large majorities but won the governor’s race for the first time in a quarter century.

Osmek snatched the Republican endorsement from two-term Rep. Connie Doepke of Orono as they vie for an open Senate seat in western Hennepin County. In a neighboring district to the southwest, Schwichtenberg is forcing Deputy Senate Majority Leader Julianne Ortman of Chanhassen to campaign like it’s November after party activists deadlocked on an endorsement.

Pugh, a former department store manager who founded the Southwest Metro Tea Party, won the GOP endorsement over Smith. His campaign website features a photograph of Republican Gov. Tim Pawlenty signing one of his bills years ago.

Pugh got involved in tea party politics when Republican Congresswoman Michele Bachmann organized a rally against the federal health care bill in Washington in 2009. Pugh is now trying to knock on more than 6,000 doors before the primary.

“People are excited to have a choice,” Pugh told The Associated Press on Friday. “They haven’t had a choice for a long, long time, if a meaningful choice ever.”

She said Smith’s solid support of organized labor prompted her challenge. According to notice of campaign donations in the weeks leading up to the primary, Smith has received at least $1,500 from unions, including the Service Employees International Union. Unions including the North Central States Carpenters and the Minnesota Nurses Association have put more than $3,000 into an independent fund working on his behalf.

Smith hasn’t filed a campaign finance report showing his campaign’s fundraising for most of the year, prompting the Republican Party to file a complaint with state regulators.

Smith did not return multiple phone and email messages from The AP.

In the same suburban area, Osmek hopes to prevent Doepke from moving up to the Senate in a campaign focused on her vote for a new $975 million Vikings stadium and accusations that she wasted government money on tropical birds.

The Freedom Club State PAC, an independently funded conservative group, has put more than $7,000 into mail pieces to help Osmek and hurt Doepke. The group is behind a website, featuring a toucan, tying Doepke to “millions of dollars of wasteful government spending, including money for tropical bird habitats in Latin America.” The accusation comes from a provision in a larger bill Doepke voted for, allowing the state to put up to $10,000 into winter habitat for Minnesota birds. The funding comes from taxpayer donations through a checkoff for non-game wildlife on state income tax forms.

Doepke, a former business executive who has the backing of local chambers of commerce, called the campaign “the dirtiest and most negative I’ve ever experienced in my life.”

Osmek said the toucan attack went “a bit too far,” and he prefers to talk about Doepke’s stadium vote and other issues where they differ.

“These proposals are big-government proposals. They are not keeping government limited and constrained, and that’s what I’m all about,” he said.

In a nearby southwestern metro district, Schwichtenberg said he is channeling voters’ disappointment with Ortman and other Republicans who took over the Legislature two years ago. He said voters expected Ortman to more aggressively attack state spending and advance causes such as a constitutional amendment that aims to weaken union clout in workplaces.

“We end up with more spending, more bonding and more taxes,” said Schwichtenberg, who said he more closely reflects what voters want.

Ortman, a 10-year Senate veteran who heads the Senate Tax Committee, said Schwichtenberg comes from “the angry faction of the Republican Party” and described herself as a strong conservative. This past session, she voted against the stadium bill and pushed to lower business taxes. Majority Republicans have to negotiate with Democratic Gov. Mark Dayton to get their ideas into state law, although Dayton can’t block them from putting constitutional amendments before voters.

“I’m conservative but I’m not angry,” Ortman said. “I think I need to work to listen to the views of others. That doesn’t make me more moderate. I think it makes me more common-sense and reasoned.”

The three closely watched contests are among 40 legislative districts with primary races on Tuesday’s ballot.