Former Massachusetts governor Mitt Romney has clinched the Republican presidential nomination.
U.S. news agencies project Romney will score a big win in the Texas primary, with more than 150 delegates at stake. This will give him more than the 1,144 delegates needed to secure the nomination.
Republicans will hold their convention in Tampa, Florida in August to officially pledge their delegates to Romney and his eventual choice of a vice-presidential running mate.
After losing the Republican race four years ago to John McCain, Romney overcame tough challenges from a raft of challengers, including Newt Gingrich, Rick Santorum, Rick Perry, and Herman Cain. All of them had at one time led Republican voter opinion polls during the campaign.
They also questioned Romney's credentials as a conservative, saying he is too moderate to be a true alternative to President Barack Obama, the Democrat incumbent.
Recent polls show him in a virtual tie with Mr. Obama, who faced no challengers for his party's nomination
Romney was not be in Texas Tuesday night to savor his victory. He was at a Las Vegas fundraiser hosted by celebrity real estate tycoon Donald Trump.
Some Democrats are criticizing Romney for not condemning Trump's assertion that President Obama was not born in the United States.
Romney, who has said he believes Mr. Obama was born a U.S. citizen, told reporters Monday he does not agree with all those who support him. But said he needs to win in November and appreciates the help of a lot of good people.