At a presser just now, Rick Perry dropped out of the presidential race and endorsed Newt Gingrich. “Newt is not perfect, but who among us is?” Perry told reporters. “There is forgiveness for those who seek God, and I believe in the power of redemption.”

“I have no question that Newt Gingrich has the heart of a conservative reformer, the ability to rally and captivate the conservative movement,” Perry continued.

This comes as video of Marianne Gingrich telling ABC News that Newt asked her for an open marriage has just gone up online.

So how much will Perry’s exit and endorsment matter in the presidential race? Will it give the anti-Romney forces a better shot at derailing Romney?

There are two levels to this question. First, how will it impact the South Carolina outcome?

I just spoke to a top official at the Tarrance Group, the GOP firm that, fortuitiously, just released a poll on the South Carolina primary. He tells me the impact will be negiligible at best, because the poll found Perry’s support in the state at less than four percent.

“It’s hard to imagine this will have a significant impact, given how low he was performing,” Brian Nienaber, the vice president of Tarrance Group, says. “If you’re a concerned voter and you’re trying to decide between Gingrich and Santorum, maybe this tips the scales a bit for you. But in terms of people who are really carrying a torch for Perry, I don’t know that his is an extraordinarily important event.

Nienaber adds that Perry supporters were “split fairly evenly between Gingrich and Romney” in terms of their second choice, perhaps making the impact even more negligible.

How will this impact the national picture? Perry has commanded very little support in recent national GOP primary polls; a recent NBC poll put him at four percent.

Beyond the national polling, the question is whether Perry’s support for Gingrich emboldens national conservatives to coalesce behind Newt. At a recent meeting of evangelical leaders, they seemed to prefer Santorum, but Santorum seems to have fizzled, and Gingrich has since surged in South Carolina polls. Perry’s line about God and redemption helps advance the storyline that is perhaps Gingrich’s best shot at allying doubts among religious leaders about him and gettting their support.

Perhaps most important, Romney has taken a terrible beating this week amid revelations about his tax rate and his offshoring. More and more conservatives seem to be raising new doubts about Romney’s electability, concluding that he’s deeply vulnerable to the Obama/Dem effort to paint him as the candiate of the “one percent” and that his past positions will make it impossible for him to prosecute the case against Obama or draw a sharp ideological contrast with him. So Perry’s exit could intensify their urgency to coalesce around Gingrich.