Iowa Republican Rep. Steve King acknowledged that he had hoped a “full spectrum conservative candidate” would have stepped forward by this point in the 2012 Republican presidential race and the fact that one hasn’t emerged has kept him from endorsing anyone in the current field.

Rep. Steve King (R-Iowa) could have a major impact on the presidential race.

King has been openly critical of Gingrich’s relatively moderate stance on illegal immigration; he has said previously that he was looking harder at the alternatives to Romney than at the former Massachusetts governor himself.

On the other end of the spectrum, King said that while both Minnesota Rep. Michele Bachmann and former Pennsylvania senator Rick Santorum are unquestionably committed to the conservative cause, neither of them has been able to generate much excitement behind their candidacies in Iowa.

“Had either of them been able to catch some momentum, this would have been easier,” said King of his endorsement dilemma. “A candidate has to have their own lift themselves off the launching pad.”

King’s struggle to settle on a candidate is indicative of the broader fluidity of the Iowa race.

While Gingrich has surged into the lead in a series of Iowa surveys conducted over the past 10 days (or so), there is also evidence that Hawkeye State Republicans haven’t made up their collective mind on a candidate.

A Des Moines Register poll showed that six in ten Iowa Republican caucus-goers could change their mind about their preferred pick; a new New York Times survey revealed that two-thirds of Iowa GOPers could switch candidates between now and the Jan. 3 caucus.

Given the lack of an electable, down-the-line conservative, it appears increasingly likely that King will not endorse anyone before the Iowa caucuses — despite his stated desire to do so as recently as a few months ago.

“I had planned to make an endorsement in September or October, ” acknowledged King, pointing out that his 2008 endorsement of former Tennessee senator Fred Thompson likely came too late to make a major difference. (Thompson finished a distant third.)

And yet, asked directly about the when and if of an endorsement, King demurred. “It is important for me to weigh in on some policy issues,” he said. “If those policy issues help shift the race.... [that’s] also a constructive way for me to be involved in this.”

That’s not exactly an encouraging sentiment for the 2012ers vying for his backing.