Actually, Huck endorsed Dewhurst months ago — a minor surprise, since Dewhurst is also supported by Huckabee friend-turned-enemy Rick Perry — but he’s starring in a campaign ad for him that was released just this afternoon. Palin’s endorsement is brand new, though, and will help boost Cruz’s profile with early voting set to start in a few days.

Two prominent blue-collar social-con Republican populists enter, one prominent blue-collar social-con Republican populist leaves:

In response to a letter from Ted Cruz, Governor Sarah Palin wrote: “We’re proud to join conservatives in Texas and throughout the nation in supporting your campaign to become the next Senator from the Lone Star State.”

“Your conservative principles, passionate defense of our Constitution and our free market system come at a time when these cornerstones of our freedom and prosperity are under attack,” Governor Palin added. “Our shared goal isn’t just to change the majority in control of the Senate, but to assure principled conservatives like you are there to fight for us.”

Ted Cruz responded, “Governor Palin has been an inspiration to conservatives across Texas and across the Nation. She is principled and passionate and never afraid to speak truth to establishment power. I am humbled and honored to have Governor Palin’s support as we fight to restore fiscal sanity to the circus that is Washington. With Governor Palin’s support, and the support of tens of thousands of conservatives from all across Texas, we will turn our country around, rein in out-of-control spending and debt in Washington, and restore the Constitution.”

According to Cruz’s campaign, they’re already seeing movement:

Campaign manager John Drogin confirmed by email to Yahoo News that Palin’s endorsement “has added HUGE buzz to our campaign.”

“Phones are ringing, online contributions are pouring in, and supporters are more excited than ever on our social networks,” Drogin wrote, adding that he’s seen a “flood” of donations but has yet to tally them.

Cruz was a logical choice for her. DeMint’s group backed him in January as a tea-party alternative to the more establishment Dewhurst, who’s been lieutenant governor for nine years and who, assuming Cruz’s fundraising numbers are correct, is being bankrolled by a relatively small number of wealthy donors. Money quote: “Dewhurst’s campaign is funded largely by those with business before the State Legislature, contributing an average of over $1,800 apiece.” There’s the crony capitalism charge, which makes him a natural fit for Palin.

So who’s going to win? According to a poll sponsored by the Conservative Republicans of Texas, Dewhurst is crushing Cruz, 51/16. Not-so-minor caveat, though: The firm that conducted the poll has been polling for Dewhurst for ages. According to PPP (a.k.a. Kos’s pollster), the race is much closer — 38/26 in favor of Dewhurst as of two weeks ago, with Cruz’s numbers trending upward at the time. I assume that Mourdock’s big win will further galvanize Texas tea partiers, as this race now becomes a golden opportunity to cement the idea of tea-party staying power. Here’s Huck’s new ad; the primary is set for May 29.