In September, Rick Perry entered the Republican presidential race to significant fanfare. Finally, conservatives thought, they had a credible alternative they could trust, and who could save the party from a Mitt Romney nomination. The Texas governor was, as was widely discussed at the time, the “savior candidate” the GOP had been waiting for.

After rocketing to the front of the pack in the early fall, Perry stumbled badly, and his campaign deteriorated as time went on. With his support in shambles, leading right-wing voices, including Laura Ingraham and Erick Erickson, have been urging the three-time governor to exit the race.

Today, Perry will follow their advice.

Gov. Rick Perry of Texas is poised to end his bid for the Republican presidential nomination, according to two Republicans close to Mr. Perry, a decision that comes two days before the South Carolina primary.

Mr. Perry will not participate in the debate here on Thursday evening, an aide said, and will make the announcement to supporters and contributors in South Carolina at an 11 a.m. press conference. He had been aggressively campaigning across the state, hoping that the first Southern primary would revive his candidacy.

CNN is reporting the same thing. Politico reports that Perry will also endorse Newt Gingrich.

There can be no doubt this is the right move for Perry and the right. The Texas governor invested millions in Iowa before coming in a distant fifth; he didn’t even make it to 1% in New Hampshire; and he’s running dead last nationally and in South Carolina. There was simply no scenario in which Perry could recover and win the Republican nomination.

In fact, his mere presence served to help the one candidate Perry finds most offensive: Romney. As the GOP field now shrinks from five candidates to four, the frontrunner suddenly has a little more to worry about in advance of South Carolina — Perry’s support, though modest, will very likely shift to Newt Gingrich and Rick Santorum, not Romney.

As for Perry, I suspect the conventional wisdom will be that it was his debate performances that did him in, most notably his infamous “oops” moment. But I think a closer look at what transpired in September and October will show it was immigration policy — the in-state tuition, followed by the governor’s “have a heart” comment — that largely caused his precipitous decline.

That said, if it was immigration that pushed Perry down, what kept him from recovering were his flaws: the guy just wasn’t prepared for a presidential campaign, could never quite explain why he should be president, and wasn’t willing to do his homework to ensure he knew what he was talking about.

Our ideas can save democracy... But we need your help! Donate Now!

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.