House Energy and Commerce Chairman Fred Upton (R-Mich.), who for the past year has been hounding the Obama administration over a failed loan guarantee to the firm Solyndra, might be developing a loan guarantee problem of his own.

But rather than being examined through a series of highly scripted committee hearings, Upton's loan guarantee connection may play out in the rough-and-tumble world of a Republican primary campaign.

This week the Auburn Hills, Mich.-based Energy Conversion Devices filed for Chapter 11 bankruptcy and said it will sell off its main subsidiary, United Solar Ovonics.

That is the same United Solar Ovonics that Upton -- along with 13 other Michigan lawmakers -- urged the Department of Energy to approve funding assistance for back in 2009 through the same loan program that funded Solyndra.

Yesterday, the powerful anti-tax group Club for Growth said that Upton's previous support for United Solar and his current investigation of Solyndra offer a perfect of example of how Upton has decided to become a conservative when it suits him.

"Every Republican supports an investigation of Solyndra -- the question is, where were you before?" said club spokesman Barney Keller. "Fred Upton has a long record of supporting market distorting energy subsidies."

The comment from Keller is particularly notable because the club, with its deep pockets and penchant for getting involved in Republican primary battles, is currently mulling whether to endorse Upton's tea party-backed GOP challenger, former state Rep. Jack Hoogendyk.

In 2010, Hoogendyk came out of nowhere to give Upton a scare in the Republican primary, losing by 14 points or about 11,000 votes. Hoogendyk's performance is even more impressive when you consider the fact that Upton spent nearly $1.5 million on the primary to Hoogendyk's $64,000.

This year Hoogendyk has lost the element of surprise and Upton is already on the attack.

A spokesman for Upton's campaign did not respond last night to the Club for Growth's latest comments, but the campaign has already sent out a news release that paints Hoogendyk as a perennial candidate (he has also run unsuccessfully for Senate). And one of the few things on Upton's barebones campaign web page is a statement on Hoogendyk's entry in the race. In it, Upton says that Hoogendyk told him just last summer that he supported the congressman and did not plan to run against him.

"My focus on job creation and commonsense reforms hasn't changed, but apparently Jack's view has," Upton wrote.

But if Hoogendyk can gain the Club for Growth's full-throated endorsement (and its checkbook), many race watchers believe that the Energy and Commerce chairman could face a serious threat come primary day on Aug. 7.

"It probably surprised Upton that Hoogendyk got that much support [in 2010], but it kind of shows you to what extent the Republican Party has moved to the right here in Michigan and elsewhere," Bill Ballenger, a longtime Wolverine State political analyst who writes the newsletter Inside Michigan Politics, said yesterday.

And Ballenger said that is not good news for Upton, a man who spent much of his 25 years in Congress honing a moderate voting record that included trying to reduce the size of the George W. Bush-era tax cuts. Upton's voice has become much more conservative over the past two years and he has used his Energy and Commerce Committee post to blast the Obama administration on everything from Solyndra and the Keystone XL pipeline to the president's health care agenda.

But the question at this political juncture is, has he become conservative enough?

Republican primary voters "want true believers on everything from the debt ceiling to holding the line on spending, holding the line of the deficit and they see Upton over the years as not doing that to the extent they'd like," Ballenger said.

But even if the Club for Growth were to go all in on the Michigan race, Hoogendyk would still have an uphill battle against the veteran congressman who has the Republican establishment at his beck and call. Upton also had a $1.7 million campaign war chest as of Dec. 31, and Ballenger expects him to start putting it to good use very soon.

"Somebody like [Sen.] John McCain when he saw a [Republican primary] challenge coming from [ex-Rep. J.D.] Hayworth in Arizona in 2010 he got out early and hard and just tore the hell out of him and bombed him with ads," Ballenger said.

Upton will likely take a page out of that playbook.

Hoogendyk said yesterday that it is not just Upton's past moderate views -- such as his one-time support for the bill to ban incandescent light bulbs -- that concern Republican primary voters. He said that Upton's recent work on the deficit reduction supercommittee and that group's failure to accomplish any real change has frustrated Michigan voters.

"He is continuing to go along, to get along with [Speaker John Boehner (R-Ohio)] and not really addressing the problems we face in terms of the budget," Hoogendyk said. "I don't have to run to the right of the guy -- I am to the right of the guy."

So far, the Club for Growth has shown more than just a passing interest in the race. Last month, it ran cable ads in Upton's southwest Michigan district blasting the congressman for not doing enough to rein in stimulus spending in 2009.

"We ran ads in this district because we believed Michigan voters deserve to know about Fred Upton's liberal record," Keller said.

But as for an actual endorsement of Hoogendyk, Keller would only say that "we're still looking at the race."

Democrats, meanwhile, say they are keeping an eye on the district, which President Obama won in 2008 after it went for Bush in 2004. The district did become a bit more conservative after the recent redistricting process.

Democrat John Waltz, an Iraq and Afghanistan war veteran and political organizer has already filed for the race.

"The problem that a bunch of Republicans have is that as far to the right as they've gone they still face primaries from the far, far right," said Democratic Congressional Campaign Committee Chairman Steve Israel of New York yesterday. "If a tea party candidate defeats Fred Upton, that district is one that we would look at with added focus. It's historically a fairly moderate district and we would look at it."