WASHINGTON — Two longtime Republicans, former Wisconsin Gov. Tommy Thompson and Rep. John Mica of Florida, turned back conservative challengers in primaries on Tuesday while 12-term Rep. Cliff Stearns of Florida was trailing tea party challenger Ted Yoho, a veterinarian and political novice.

Yoho’s strong showing was the surprise of the night as four states held primaries, including Connecticut and Minnesota. He was ahead of Stearns by less than 900 votes, complete but unofficial primary results showed.

Yoho’s anti-incumbent campaign was boosted by a television ad with actors dressed as politicians in suits eating from a trough alongside pigs and throwing mud at each other.

Stearns, who is chairman of an investigations subcommittee for the House Energy and Commerce Committee, has led high-profile probes of the failed California solar energy company Solyndra as well as Planned Parenthood.

Thompson turned back a trio of challengers to win Wisconsin’s Republican Senate primary, setting up a general election race against Democratic Rep. Tammy Baldwin for retiring Democratic Sen. Herb Kohl’s seat. The GOP hasn’t held it since 1957.

Thompson’s win, as an establishment Republican derided by rivals as not conservative enough, was a disappointment for tea party forces and other conservative activists hoping to add to big wins earlier this year in the Indiana and Texas GOP Senate primaries. Tea party candidates scored major gains in the 2010 congressional races, but they’ve had mixed success since then.

The win marked the first step in a political comeback for Thompson, 70, a former Cabinet secretary who hasn’t been on the ballot since 1998.

He beat former U.S. Rep. Mark Neumann, businessman and political newcomer Eric Hovde, who spent at least $4 million on the race, and state Assembly Speaker Jeff Fitzgerald. Neumann had support from tea party forces as well as the anti-tax group Club for Growth.

Thompson’s challengers cast themselves as closer than Thompson to today’s more conservative GOP.

Wisconsin Republicans hope they can build momentum from GOP Gov. Scott Walker’s recall win in June and Republican presidential candidate Mitt Romney’s decision to tap native son Rep. Paul Ryan as his running mate. The GOP sees the Senate race in Wisconsin as a pickup opportunity as they try to gain majority control from the Democrats.

Thompson enjoyed the most name recognition statewide as a governor for 14 years who was first elected to political office in 1966. He got a late boost from Ryan, who praised Thompson’s record as governor during a rally in Wisconsin on Sunday. Ryan did not mention Thompson’s rivals. Thompson aired a radio ad on Monday featuring Ryan’s comments.

In Florida, Mica, a 10-term congressman who wields considerable clout as the chairman of the House Transportation and Infrastructure Committee, is expected to win in November in his Republican-leaning district. Tea party freshman Rep. Sandy Adams fell short in his bid against Mica despite backing from 2008 GOP vice presidential candidate Sarah Palin.

Mica and Adams landed in the same central Florida district due to redistricting, and the result was a nasty member-versus-member primary.

The Florida contest was a prime example of the sharp split in the Republican Party this election season between grass-roots conservatives and the GOP’s establishment candidates.

Mica overcame criticism by Adams that the big-spending ways of longtime lawmakers and Washington insiders like him have fueled the nation’s soaring debt, a charge that echoes the deep divisions in the GOP. The two tangled over spending for pet projects and who’s more conservative.

Also in Florida, Democratic Sen. Bill Nelson will face Republican Connie Mack IV in November after each won handily in their respective party primaries.

In Connecticut, wealthy former wrestling executive Linda McMahon, the GOP’s endorsed candidate, defeated former Rep. Christopher Shays in the Senate primary. Sen. Joe Lieberman, an independent, is retiring.

Shays, a moderate who had represented a district anchored by Greenwich and other wealthy suburbs outside New York City since 1987, lost his seat in 2008. He had hoped his Washington experience could blunt McMahon’s wealth and official party support.

McMahon spent about $50 million of her own money in her failed 2010 Senate race. It was the largest amount of money spent on any campaign in state history, as well as the largest amount per vote nationwide. She outspent Shays and attacked him as a career politician.

In Connecticut’s Democratic Senate primary, Rep. Chris Murphy, who was the party’s endorsed candidate, beat former Secretary of the State Susan Bysiewicz. Looking past Shays, McMahon has already aired an attack ad against Murphy.