Candidates look to Texas for big wins

— -- Texas, the second-most-populous state with nearly 24 million residents, is the biggest prize in Tuesday's presidential contests. USA TODAY takes a look at the Lone Star State's politics.

Polls close:

7 p.m. CT/8 p.m. ET except in the El Paso area, which is one hour behind.

Delegates at stake:

193 for Democrats, 137 for Republicans

Polling

Democratic 'super delegates'

Of the state's 35 elected officials and party insiders who get to vote at the national convention, 18 have made endorsements. Hillary Rodham Clinton has lined up the support of party veterans such as former House speaker Jim Wright and key Hispanic lawmakers such as House Intelligence Committee Chairman Silvestre Reyes. Barack Obama's supporters include centrist Democratic Rep. Chet Edwards, whose district includes President Bush's ranch near Crawford, and Rep. Charles Gonzalez, whose father, Rep. Henry B. Gonzalez, was a protégé of President Lyndon Johnson.

Key voting blocs:

Non-Hispanic whites make up 48% of the population, while 36% of Texans are Hispanic and almost 12% are black. Nearly one-third of the Hispanic voters are ages 18-29.

Party registration:

Texans don't register by party, so voters can cast ballots in either the GOP or Democratic contests. President Bush's home state has trended Republican over the past decade, but early voting returns show the Democratic race is drawing the most interest: Through Thursday, 717,469 people had voted in person or by mail in the Democratic primary; 242,197 voted GOP.

Texas two-step:

Democrats can vote twice for president — and do it legally. First, they can vote in the primary, which will allocate 126 delegates. Then, at 7:15p.m. CT on Tuesday, voters who have receipts that prove they cast ballots in the primary can participate in precinct caucuses, which begin the process of awarding 67 more delegates.

The GOP race:

Texas Rep. Ron Paul hasn't campaigned much lately for the White House, so he can fight off a primary challenger in his congressional district. …John McCain has picked up major Texas endorsements since emerging as the GOP front-runner. They include Gov. Rick Perry and both U.S. senators, Kay Bailey Hutchison and John Cornyn. Hutchison has been mentioned as a possible running mate, but she denies interest. Cornyn once got into a heated flap with McCain over immigration policy. …Mike Huckabee, who hails from neighboring Arkansas, is supported by Rep. John Culberson of Houston and state Sen. Dan Patrick, a conservative radio talk-show host.