On a four-state primary night, Clinton also took Ohio and Rhode Island, while Obama won Vermont.
But the Texas race wasn't over with the primary vote: Caucuses were still proceeding -- some just beginning -- after midnight. Obama was the preferred candidate of 54 percent of caucus-goers in the handful of caucuses reporting.
The two candidates saw their best results in parts of Texas where they spent the most time campaigning -- Clinton in predominantly Hispanic South Texas and Obama in major metropolitan areas. Obama also won in the college towns of Austin, the state's most liberal city where the University of Texas is based, and in Brazos County, home to Texas A&M University.
"I am thrilled at this vote of confidence from the people of the great state of Texas, a state that I know and love," she said.
Before several hundred supporters in San Antonio, Obama said, "No matter what happens tonight we have near the same delegate lead as we had this morning and we are on our way to win the nomination," Obama said.
While Obama enjoyed a strong showing in Dallas-Fort Worth and Houston, Clinton held the advantage in Bexar, Nueces, Hidalgo and other counties in South Texas.
The strength of Clinton's lead among Hispanic voters was surprising, even though she was expected to do fare better than Obama, said political scientist Jerry Polinard at the University of Texas-Pan American. "I think he expected to cut into her Latino vote a little bit more than that," he said.
Clinton had counted on Latinos, who comprised 30 percent of the Texas Democratic primary vote, to help her in a state where she and former President Bill Clinton have political ties dating to the early 1970s. She was winning two-thirds of the Hispanic vote.
Her familiarity in the Latino community and her continued message of "experience, experience, experience" ensured that she did well with Hispanics and kept the race close, Polinard said.
Exit polls showed that Obama won heavy margins among black voters, with a nearly 6-to-1 edge. Blacks accounted for 20 percent of the Democratic primary voters.
Overall voter turnout set a state record at 28 percent and some polling places were still open at midnight.
"This is a historic election, and you are seeing historic turnout," said state Democratic Party spokesman Hector Nieto as party officials monitored delegate counts and caucusing from their Austin headquarters.
In the Republican race, Texas gave John McCain the delegates he needed to clinch the GOP nomination. Mike Huckabee immediately dropped out of the presidential race and pledged he would work for party unity. The former Arkansas governor had hoped Texas' social and religious conservatives would boost his struggling candidacy.
But with McCain so close to sealing the nomination, there was little interest in the Republican race in Texas compared with the close Democratic presidential contest, and large numbers of voters in conservative pockets of the state opted to vote in the Democratic primary.
In Collin County, one of the state's most Republican counties, Democratic turnout was five times its normal size, according to local media reports.
McCain had the backing of state GOP elected officials, including Gov. Rick Perry, who originally endorsed moderate Republican Rudy Giuliani and irritated some in his social conservative base with that decision. His later choice of McCain -- who's not a favorite of some hard-line conservatives -- didn't go over well either with social conservatives, but that irritation didn't help Huckabee.
Texas will send 140 delegates to the national GOP convention, almost all awarded based on the primary vote.
Texans didn't wait until Election Day to vote in large numbers. An estimated 2 million people showed up during two weeks of early voting.
In a complex system, nicknamed the "Texas Two-step," Democrats have 193 pledged delegates to dole out based on primary vote results and a series of caucuses that began after the polls closed, some grossly delayed by long lines of voters still in line at midnight. Thirty-five others are unpledged delegates. Only voters who cast a ballot in the Democratic primary could take part in a caucus.
Texans didn't expect to figure prominently in the presidential nomination race after the Legislature declined last year to move up the state's primary to Feb. 5, leading to widespread speculation that the presidential nomination would be decided well before the race ever got to Texas.
At times the presidential race overshadowed other races on the Texas ballot.
State Rep. Rick Noriega led a crowd of four Democrats competing for their party's nomination for U.S. Senate. The winner will face Republican Sen. John Cornyn, who had nominal primary opposition.
In congressional races, Shelley Sekula Gibbs and former Cornyn aide Pete Olson led a field of 10 Houston-area Republicans to become the one to face U.S. Rep. Nick Lampson in the fall, while Republican Lyle Larson won the primary and will face Democratic incumbent Rep. Ciro Rodriguez in the fall.
Several Democratic Texas House members closely tied to Republican Speaker Tom Craddick tried to fight off primary challenges from opponents who took issue with their alliance with Craddick. The speaker, criticized from some legislators in both parties as too iron-fisted, took control of the House in 2003.
Republican primary voters approved three ballot resolutions urging that federal immigration laws be upheld, that voters be required to have a photo ID and that local spending be limited unless there's voter approval.
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