This seems signfiicant: GOP Senator Bob Corker said on MSNBC just now that hiking the debt ceiling in stages — as the House GOP plan calls for — could fuel economic uncertainty, lending support to a key Democratic argument against the Boehner plan.

Here’s the key exchange, with Chuck Todd a few moments ago:

TODD: Considering everything we’ve seen this week on a vote on any debt ceiling, do you want to go through this in six months?

CORKER: I would love to see us go ahead and achieve all the savings that we can get right now. Again, I’d like, of course, to push it towards $4 trillion which is what the markets have kind of said we need to do, but I do agree with the, fact that, you know, having these debates in the middle of an economic downturn that we’re having right now is not healthy, and there’s no question that business people, those people that hire employees all across our country watch this and become uncertain.
So, in a perfect world — and I know we’re not in a perfect world — but if we can get worked out over the next several days something that actually achieves all those on the front end and extends the debt limit beyond this next election, to me that would be a perfect solution and I hope we can do that.

In a follow up interview with me, Senator Corker expanded on the claim, though he added some nuance. He said that he wasn’t criticizing Boehner’s approach — which he described as merely “getting the ball rolling” — and clarified that for him, the size of spending cuts is ultimately more important than whether the debt ceiling is increased beyond 2012. “If it took multiple debt ceiling hikes, I’d rather achieve the savings,” Corker said.

But the Senator left no doubt that he preferred a one-shot debt ceiling increase for the sake of the economy. “It would remove the uncertainty that people all across the country feel,” he said, adding that it would give ”confidence” to those “who buy and rate treasuries.”

Corker said he could very support short term hikes if they were being pursued in order to give lawmakers time to reach a larger deal. But asked to respond to Republicans who want multiple debt ceiling hikes over time in order to force the President to raise it in an election year, Corker said: “I’m not in that camp...I want to see the economy rebound.”

Here you have a Republican Senator using the key GOP “economic uncertainty” argument to undercut the idea of multiple debt ceiling increases. Corker has also said he finds shortcomings with Harry Reid’s propoposal — he has claimed it could lead to downgrades — and given the level of spending cuts he’s seeking, you can’t imagine him endorsing the Reid plan anytime soon. But given what Corker said here, I wouldn’t be surprised if you see more GOP senators in the days ahead moving towards the idea of some kind of compromise built around the single debt ceiling increase that Senate Dems and Obama want.