A last-minute shocker before the filing deadline, although you can understand the logic. Bigger conservative names in Texas had already passed on challenging Cornyn despite tea-party perceptions that he’s an incorrigible RINO. Steve Stockman looked at what grassroots righties did for Ted Cruz against the much better-funded David Dewhurst last year and figured … why not? What does he have to lose?

Stockman, a far-right conservative who has called for the president’s impeachment, filed for the seat minutes before the 6 p.m. local deadline, confirmed Spencer Yeldell, a spokesman for the Republican Party of Texas. Cornyn, whose $7 million cash-on-hand far outstrips Stockman’s $32,000, is still the heavy favorite, but the latter’s entry into the race could force the incumbent senator to tack farther right as he tries to win over a corner of the party that has recently been skeptical of him…

But Stockman is a highly recognizable name in some circles, and he looks to be a game-changer. The 57-year-old made waves earlier this year when he returned to the House — where he previously served from 1995-1997 — with his calls to impeach President Barack Obama. And he’s not been shy about his other deeply conservative, and sometimes controversial, views on issues ranging from gun rights to immigration. He has also likened Obama to Saddam Hussein and urged America to withdraw from the United Nations…

“We haven’t decided yet whether we will endorse Steve Stockman, but we’re glad he is running,” Matt Hoskins, the [Senate Conservatives Fund] leader, said in a statement. “Texas deserves two conservative fighters in the Senate, not just one. John Cornyn has voted to increase the debt, raise taxes, bail out Wall Street banks, and fund Obamacare. He’s part of the problem in Washington and voters deserve an alternative.”

Cornyn has a war chest of $7 million to spend, precisely for this sort of contingency. Stockman has a war chest of … $32,000 versus $163,000 of debt. There’s not much time for him to move the polls either. Ted Cruz announced his Senate candidacy in January 2011, more than a year before the primary. Stockman, in announcing yesterday, left himself less than three months. And unlike Cruz, there’s already some dirt on him uncovered by reporters that his opponent might use. If he lands a big endorsement, though, that might boost his name recognition enough to push him into a run-off with Cornyn, where he stands a fighting chance. (Remember, Cruz actually finished behind Dewhurst in the primary last year before crushing him in the run-off a few months later on a wave of conservative support.) Whose endorsement is big enough to propel him, though? Cruz’s might be, but Cruz reportedly told his colleagues in the Senate that he won’t campaign against them. The backing of the Senate Conservatives Fund or Heritage Action would help, but maybe they’re too consumed with beating Mitch McConnell to give Stockman the sort of full support he’d need to hurt Cornyn. He needs a big surge of grassroots excitement to offset that money advantage. Maybe conservative media can help him do that, although in that case I would have guessed that he’d make the announcement that he’s running on Red State or some talk-radio show. Nope. It was at WND.

It’s worth clicking and reading the latter, incidentally, to see how he’s leaning on Cruz’s brand in Texas to try to jumpstart his own campaign. It was Cornyn’s betrayal of Cruz during the “defund” effort, he says, that motivated him to run. “If you disagree with someone, that’s fine, but I really believe you should do it privately, not so publicly,” he told WND. “[Cornyn] made a big show of removing his name from a letter supporting Cruz.” True, but Cruz is no slouch when it comes to disagreeing with other Republicans publicly. He described “defund” skeptics in the congressional GOP as the “surrender caucus” and then compared Senate Republicans who voted to end the shutdown to an air force bombing its own troops in the House. But oh well. Politics ain’t beanbag — if you’re a RINO and have it coming.

Update: “Liberal John Cornyn wakes up every morning and works to make the Senate a more liberal place.”

Update: A blow to Stockman:

Update: Just got an e-mail from Dan Holler, communications director from Heritage Action, emphasizing that the group doesn’t get involved in primaries, only in legislative action like the “defund” effort. There’ll be no endorsement of Stockman or of anyone else in an intraparty GOP battle.