BOISE - Idaho Republicans stage their first-ever closed primary election Tuesday, where only registered members can vote in GOP balloting.

But debate over whether voters will stay home, rather than be forced to publicly declare partisan affiliation, is being overshadowed by political theater from within the state's dominant party.

House Republican leaders are waging internal warfare, seeking to depose their own GOP incumbents by financing libertarian-leaning political action committees. Rival pro-business groups have joined the fray with independent ads of their own.

Even Mitt Romney's March 6 "Super Tuesday" presidential caucus win has become an issue, with Ron Paul loyalists plotting against him.

These developments mark the evolution of a four-year-old intraparty fight where conservative, tea party-influenced activists seek to remake the Idaho GOP in their image, while establishment Republicans fear straying from the broader, pro-business message that helped them win four-fifths of the Legislature and all statewide offices since the early 1990s.

"This is the meanest dang campaign I ever saw," said Sen. Denton Darrington, R-Declo, retiring after 30 years in the Senate. "It's the strangest, weirdest political season I've ever seen, and that's a lot of years."

For all the furor surrounding legislative races, it pales in comparison to some unusual local Republican contests.

In one, Shaun Winkler, a Ku Klux Klan imperial wizard, faces incumbent Bonner County Sheriff Daryl Wheeler in the race to be the top law enforcement officer in Idaho's rural north. Winkler, 33, held a cross-burning near Priest River last week.

Issues that many Idaho Republicans thought settled also have re-emerged.

On March 6, Romney won the "Super Tuesday" Idaho caucus easily over Paul, the libertarian-leaning Texas congressman.

But Paul loyalists including Ryan Davidson have said they're targeting obscure local GOP precinct committee leader races, in hopes of sending friendly delegates to the state Republican Convention in Twin Falls in June to reverse Romney's caucus win.

Debbie Field, a former GOP state legislator and Romney organizer, is flabbergasted. She points out that many Paul backers wanted the caucus, thinking it could help the libertarian-leaning Texas congressman's chances.

"It's amazing," Field said. "When they don't get the results they want, they change the rules. It's a strange way of functioning."

Davidson declined comment.

Democrats who are holding their own nominating contests Tuesday are observing the machinations from the other side of the aisle - not without a little relish.

Idaho Democratic Party chairman Larry Grant hopes this "Republicans-eating-their-own" vibe translates to his party's success in November's general election, especially if ideological libertarian-leaning Republicans win out.

"It's definitely a battle between the extremists and the more-extreme," Grant said, calling it "a full-fledged fight for the soul of the Republican Party."

State Rep. Bob Nonini, R-Coeur d'Alene, spent at least $12,000 on efforts to defeat fellow Republicans he doesn't like - nearly four times what he reported spending on his own campaign in the latest finance disclosures.

Meanwhile, House Speaker Lawerence Denney and Majority Leader Mike Moyle chipped in at least $15,000 to a political action committee, GunPac, that's working to oust at least six Republican incumbents, including House Majority Caucus Chairman Ken Roberts, R-Donnelly.

Besides Roberts, others on GunPac's opponent list include Reps. George Eskridge of Dover and Christy Perry of Nampa; and Sens. Shawn Keough of Sandpoint, Dean Cameron of Rupert and Patti Anne Lodge of Huston.

Lou Esposito, the Boise-based political consultant behind GunPac and three other conservative PACs agitating behind the scenes in 2012 primary races, is hopeful Tuesday's outcome will be a harbinger for the Idaho Republican Party's shift toward a more-conservative ideology.

Still, Esposito insists the divide between pro-business groups and the list of 40 candidates he's supporting isn't as wide as some suggest.

"There's a number of races we've been playing on the same side, there's a number where we've been going head to head," he said. "We'll see where the dust settles."

The Idaho Association of Commerce and Industry and the Idaho Association of Realtors have also been spending thousands on campaign flyers to help Republican candidates in races targeted by Esposito's PACs.

John Eaton, the realtors' lobbyist, said he's concerned Idaho's GOP is being infiltrated by other parties' members who are adopting a popular brand to boost their ballot-box chances.

Eaton points to Maurice Clements, a former Idaho GOP House member in the 1970s who switched parties in 1988 to run as a Libertarian.

Clements is challenging Lodge in the Senate District 11 Republican primary.

"Constitutionalists and Libertarians have come into the Republican Party just to get elected," Eaton said.

Republican Secretary of State Ben Ysursa is hoping flamboyant local races, whether for Bonner County sheriff or for bitterly-contested legislative seats, will help bolster traditionally low primary election turnout that hovers around 25 percent.

But Ysursa thinks having to publicly declare to which party they belong might keep some voters away.

The first-ever closed GOP primary was something demanded by some conservatives concerned that independents and Democrats were crossing over and skewing the Republican primary toward un-Republican candidates.

"I'm predicting 23 percent turnout," Ysursa said. "I hope I'm wrong."