There's a Texas-sized stumbling block on Sen. Hillary Rodham Clinton's comeback trail.
Even Clinton's most devoted surrogate -- her husband, Bill Clinton -- acknowledged the do-or-die stakes on Wednesday in Beaumont, Texas, conceding that a loss in Texas or Ohio would likely doom her candidacy.
"If she wins Texas and Ohio I think she will be the nominee. If you don't deliver for her, I don't think she can be. It's all on you," the former president told the audience at the beginning of his speech.
A series of demographic and organizational challenges are coming together to make the Lone Star State an extraordinarily difficult venue for Clinton, with her campaign needing a decisive win to overcome Sen. Barack Obama's growing edge in convention delegates.
With polls showing the race essentially tied, several independent political analysts say that even if Clinton takes an overwhelming share of Latino voters, she will be hard-pressed to carry the state, much less capture a large share of delegates.
And the unique way that Texas awards delegates could force Clinton to take as much as 55 percent of the state's vote just to break even in the battle for delegates, said Richard Murray, director of the University of Houston's Center for Public Policy.
"They've gotten some bad breaks here," Murray said. "Texas is not well set-up for her, and the Obama people have figured that out. It's tough — but they've got no choice. They must win down here, and win convincingly."
Texas is the biggest prize remaining on the Democrats' schedule. It's a virtual must-win for Clinton, D-N.Y., who has dropped 10 contests in a row to Obama, D-Ill.
March 4 voting in the Texas primary — which will allocate 193 convention delegates — provides Clinton's best opportunity to jump back into the race, with the state's large Hispanic population providing an apparent edge to Clinton.
But a few significant quirks could frustrate the Clinton campaign. For starters, Texas has a one-of-a-kind primary/caucus system, where two-thirds of the state's delegates will be awarded in the March 4 primary, while the remaining third will depend on the results of caucuses later that evening.
Voters are permitted — and, in fact, are encouraged by campaigns — to attend both events.
But Obama has demonstrated organizational strength in other caucus states, leaving him favored to emerge with the larger share of the 67 delegates at stake in the caucuses, regardless of what happens in the primary earlier in the day.
Another factor in Obama's favor is the open nature of the primary.
Texas — like Ohio, the other big state that votes March 4 — allows independents to vote in the Democratic primary, a dynamic that has significantly favored Obama in other states, including Wisconsin, which voted on Tuesday.
In addition, Texas Democrats have designed a system of delegate allocation that rewards parts of the state that have voted heavily Democratic in previous elections.
This means that many of the areas the Clinton campaign is most heavily targeting — particularly the Latino-heavy communities in the Rio Grande Valley — carry less weight than some of the urban areas that favor Obama.