Eastern Idaho is home to scenic mountains and rivers, a bountiful potato crop, and now, a heated battle between the business wing of the GOP and the tea party.

The U.S. Chamber of Commerce came to the defense of Rep. Mike Simpson (R-Idaho) Thursday by launching a TV ad meant to bolster his standing against a primary challenger running to his right. "Conservative, Idaho strong," says the narrator of Simpson in the 30-second commercial.

Others would disagree. Like the Club For Growth, for example, an anti-tax group that is backing attorney Bryan Smith, who hopes to unseat the congressman.

"It’s no surprise that Mike Simpson is receiving support from his allies in Washington,” said Club For Growth President Chris Chocola. “Mike Simpson supported the $700 billion bailout out of Wall Street. The Chamber of Commerce supported the $700 billion bailout of Wall Street."

It's the latest front in what promises to be a heated competition in various contests around the country pitting the business wing of the GOP against a conservative, tea party base.

The development in Idaho comes on the heels of a government shutdown and debt ceiling standoff in Washington that irked much of the business community because of the destabilization and uncertainty it caused. Now, the business movement is resolved to redouble its efforts to install and protect candidates who will represent their interests, which sometimes clash with the all-out political warfare and unwavering conservatism championed by the tea party wing of the GOP.

"With America’s job creators facing historic uncertainty, our number one focus is on jobs and growth," said Rob Engstrom, the chamber's political director. "It’s time to get back on offense to get the economy moving again. Our efforts in Idaho are designed to back candidates who support American Free Enterprise and oppose those who stand in the way."

The chamber spent big money in Alabama's 1st district special election. It's preferred candidate there -- Bradley Byrne -- survived a spirited challenge from Dean Young, an insurgent tea party candidate who lost no sleep over the government shutdown.

Young lacked a real campaign apparatus or network of support -- the Club didn't back him, nor did most national tea party groups -- yet he still came within reach of an upset. The closeness of the contest underscores how critical it will be for business groups to invest in races where their candidates are under attack.

Idaho's 2nd district contest is one such contest. And the candidates there could hardly be more different. Simpson is a close ally of House Speaker John Boehner (R-Ohio). Smith names Rep. Justin Amash (R-Mich.) and Sen. Ted Cruz (R-Tex.) among others as the leaders on Capitol Hill with whom he is aligned. Cruz led the charge to try to repeal Obamacare in the budget debate, while Amash has clashed with House GOP leadership and looks to also be a target of business interests in a primary next year.

Adding to the intrigue is Mitt Romney, who is in Simpson's corner. Romney is popular in Idaho; the state has a large Mormon population, and both Romney and Simpson belong to the Mormon Church.

As the GOP continues to try to sort out its internal divisions, one of the most telling story lines of the 2014 campaign will be how and where business and tea party interests clash on the campaign trail. For now, this much is for certain: Idaho's 2nd district promises to be significant staging ground for that fight.