BOISE (AP) — Since last week, pro-business groups like the Idaho Association of Realtors have pumped some $30,000 into campaigns of Republican incumbents facing libertarian-leaning rivals in the May 15 primary.

In northern Idaho, Sen. Shawn Keough, of Sandpoint, and Rep. George Eskridge, of Dover, each banked at least $5,000 from donors including grocers, hospitals, insurers and real estate agents. Others to benefit were Sen. Patti Anne Lodge, of Huston, who faces Maurice Clements, a former Idaho GOP legislator in the 1970s who ran unsuccessfully as a Libertarian in 1988.

Keough contends that pro-business groups have aligned themselves with incumbents like her because they’re concerned their rivals might have run as Libertarian or even Constitution Party candidates in the past.

“The folks that are challenging the incumbents aren’t necessarily reflective of Main Street Republican values,” Keough said. “It’s indicative of what you’ve been seeing in terms of the split in the party the last four years.”

John Eaton, the Idaho Association of Realtors top lobbyist, says his group gave Lodge $1,000 last week, on grounds she offers the most consistency for businesses than Clements.

“He’s the perfect example,” Eaton said. “He wants to legalize pot. That’s the kind of stuff that the business community would never support.”

Clements has favored the decriminalization of marijuana, to help remedy growing prison populations, the Idaho Press-Tribune in Nampa has reported.

He didn’t return a phone call Monday seeking comment.

Within 16 days of the primary, contributions of $1,000 must be reported by candidates within 48 hours.

Idaho secretary of state records show groups adding to Republican incumbents’ reserves in this period include the Northwest Grocery Association, the Idaho Hospital Association and Blue Cross of Idaho, as well as Micron Technology Inc. and J.R. Simplot Co.

Though this business cash is flowing to incumbents, supporters of their libertarian-leaning challengers aren’t sitting idly by.

Political action committees like the Free Enterprise PAC are pumping independent expenditures into glossy campaign mailers aimed at unseating incumbents like Keough and Eskridge.

Each has a tea party rival, with Keough facing Danielle Ahrens and Eskridge up against Pam Stout, made famous by her 2010 interview with talk-show host David Letterman about the conservative grassroots movement.

Larry Knapp, the Boise-area real-estate agent behind the Free Enterprise PAC, didn’t return a phone call seeking comment.

But in a mailing this week, he labels Keough as Idaho’s “No. 1 big spender” — and questions her Republican credentials. “Too many ‘Republicans’ think big government is the solution,” Knapp wrote. “That is just foolish and it’s killing jobs.”

Knapp also links Eskridge’s support for alternative energy tax breaks in Idaho to President Barack Obama, telling prospective GOP voters in Bonner and Boundary counties, “George Eskridge thinks he can pick winners and losers.”

Eskridge, first elected in 2000, insists he’s a conservative, regardless of what foes say.

Business groups know it, too, he said, resulting in their support for his campaign.

“They know what my record is,” Eskridge said. “And they know we have a tight race up here.”

Stout, who said she doesn’t know Knapp and has never spoken with him, distributed her own campaign flyer to District 1 voters last week highlighting, among other things, Eskridge’s 2011 vote opposing an Idaho-led push to nullify the federal health care overhaul.

Still, Stout feels a bit like an underdog given her rival’s support from businesses.

“It’s obvious from the number of pieces of mail that they’re putting out, they have huge corporate backing,” she said. “Basically, I’ve gone into my retirement accounts.”

— For more information on 2012 campaign finances in Idaho http://www.sos.idaho.gov/elect/Finance/2012scan.htm