Texas Lt. Gov. David Dewhurst (R), running for reelection, talks to supporters and the media in Houston in March. (Richard Carson/AP)

Updated to reflect Dewhurst's loss Tuesday.

Texas Lt. Gov. David Dewhurst (R) lost his reelection bid today, in what is merely the latest huge setback (and a potentially fatal blow) in a once-promising political career that once had the wealthy second-in-command on a crash course for the U.S. Senate.

In doing so, Dewhurst becomes the first big-name Republican to lose two primaries against the tea party — and only two years apart.

So what the heck happened to David Dewhurst?

In sum: The seeds for his loss were planted long ago, and it's not all his fault. But there are plenty of lessons available for other Republicans seeking to avoid similar fates.

Here are a few:

1) Blood in the water will draw sharks

Dewhurst, you might recall, was considered the favorite to join the Senate whenever a Texas seat opened up — so much so that it seemed like he might even get a rare free pass. His name cropped up as a would-be senator as early as 2009, when then-Sen. Kay Bailey Hutchison (R) said she would resign to run for governor in 2010.

Hutchison later opted to finish out her term, meaning the race to replace her was set for 2012. Then, of course, Dewhurst ran into a guy named Ted Cruz.

Holding the race in 2012 seemed like a good thing for Dewhurst; after all, he could run for Senate while keeping his day job, which wasn't up for reelection until this year. But his loss this year shows that even a seemingly win-win situation can lead to a political loss. Dewhurst's defeat to Cruz effectively left blood in the water, and a coterie of Republicans soon lined up to challenge him.

State Sen. Dan Patrick (R) wound up winning earning the runoff with Dewhurst, beating him by double digits on primary day. But Dewhurst would likely have been vulnerable against basically anybody with conservative bona fides.

2) You never know whom the tea party will target

Like a lot of Republican politicians who find themselves on the receiving end of a tea party offensive, Dewhurst isn't exactly a moderate. He just happened to be a guy who was a little too close to the political establishment and appeared vulnerable.

The tea party definitely likes to target moderates, let there be no doubt. But what it likes more is to install its allies in whatever offices they can win. And Dewhurst's office was one they could win.

3) The tea party needs a vessel

What the tea party needs even more than a winnable seat is a candidate who is capable of winning it. And the best recipe for success is a candidate who can raise money like an establishment candidate.

Patrick did this. While Dewhurst has spent millions of his personal fortune over the course of his career, Patrick outraised him two-to-one in the closing months of the campaign.

4) Immigration matters, though it's not sufficient by itself

Gov. Rick Perry's (R) support for in-state tuition for illegal immigrants was a notable stumbling block in his full-of-stumbles 2012 presidential campaign. And now, it helped end the career of his longtime second-in-command, too.

Dewhurst's past support for the same thing was a focal point of Patrick's campaign.

The last time immigration reform was key in a GOP primary was a few weeks ago, when Rep. Renee Ellmers (R-N.C.) found herself targeted by national conservatives over her support for a path to citizenship for those who are here illegally.

Despite facing an opponent with very little funding, Ellmers took less than 59 percent of the vote. That's still a clear victory, but it's pretty rare that an incumbent falls below 60 percent.

The lesson: Like a lot of conservative litmus-test issues, voting the wrong way on immigration issues isn't a death wish, but it can hurt you if other necessary conditions are met (see above).

5) Little things can reverberate for years

As Reid Wilson noted a couple months back, one of the most notable twists in Dewhurst's career was when the 2012 Texas primary was delayed nearly three months because of uncertainty over redistricting.

The primary was moved from early March to late May, giving Cruz's campaign more time to catch on against the early favorite.

We'll never know whether things would have turned out differently for Dewhurst if that delay had never occurred -- perhaps he'd be a senator today -- but we're guessing he'd like to know.