Barring a miracle, this is Rick Perry's final act in the 2012 elections. On Saturday, he will come in last in South Carolina. It will be only the third time in a generation Rick Perry has lost an election, with the only other two times being Iowa and New Hampshire this year.For a generation, Rick Perry was undefeated. Now he will go back to Texas and everyone who ever lost to Rick Perry will seek to settle old scores. It will be a tough, bloody fight. He will have to be ready for it.Perry, however, has a potential trump card up his sleeve as he rebuilds political capital. It's simple: he can drop out today, and endorse someone else. Doing so today, before the CNN Debate tomorrow, gives the news time to sink in.But who to endorse?Mitt Romney makes no sense. To endorse Romney would be to turn Perry's message throughout the campaign into a joke. It would buy Perry no good will. He would return to Texas a joke.Rick Santorum makes no sense either. While closer to Perry than Romney on some points, Perry campaigned on reducing the size and scope of Washington, privatizing social security, and fixing entitlements. Endorsing Santorum may leave Perry in good stead with his fellow evangelicals, but it would fly in the face of the limited government principles he outlines both on the campaign trail and in his national bestseller Fed Up!Then there is the man who wrote the introduction to Fed Up!, former Speaker of the House Newt Gingrich.I'm willing to bet that among activists in Texas, Newt Gingrich is more popular than Romney. His message has been rather consistent to Perry's, including a man on a mission to gut Washington, D.C. While Gingrich lacks Perry's limited government bona fides, he is the only other candidate in the race emphasizing that business as usual in Washington is not acceptable if the nation we love is going to survive - as Gingrich wrote in his introduction: "Devolving power out of Washington is critical to our long-term survival." And that's the truth.If Rick Perry stays in the race, conservatives opposed to Mitt Romney will be legitimately able to blame Rick Perry for dragging down either Newt or Santorum. If the person he endorses doesn't win the nomination, it still doesn't hurt him as much as staying in to take a few deciding votes. Huntsman has already done his part to help Romney. Perry's endorsement today or tomorrow morning could offset that, shifting undecideds and Perry's own voters to someone else and get them a leg up on Mitt Romney. With Newt Gingrich surging according to the latest Rasmussen poll and Sarah Palin saying she'd support him, Perry's withdrawal and endorsement before Saturday could ensure a Gingrich win.Rick Perry's campaign has come to an end. But he could leave on an unexpected high note — helping conservatives unite around one not-Romney in a way no one else has been able to. Rick Perry could be the catalyst and kingmaker so many have been looking for, even as other conservatives have stood by, unwilling to endorse in the face of long odds.Rick Perry has come this far motivated by his faith and his principles. He has fought the good fight. He has not forgotten what is due to his own honor and that of his country. But now he has a choice to make, and I wish him wisdom in it.Either Rick Perry will leave the race Sunday with no political capital and no deposit of goodwill an endorsement would bring, or he will choose to strike one final blow for limited government conservatism.