Republican Mitt Romney has secured his place as the challenger to Barack Obama in November’s US presidential election, following a primary in Texas.
Projections show Mitt Romney easily won enough votes to pass the threshold of 1,144 delegates needed for the nomination.
Mitt Romney said he was “humbled”. He is the first Mormon from a major party to contest the presidential election.
He is set to be officially anointed as the Republican nominee at the party convention in Florida in late August.
Mitt Romney has been the presumptive nominee for several weeks as his rivals withdrew or suspended campaigning.
With 1,086 delegates secured as he entered the Texas race, Mitt Romney only needed 58 to pass the 1,144 mark.
In early returns, Mitt Romney had captured more than 70% of the vote. Texas awards 152 delegates proportionally.
He will surpass his father, George Romney, a former Michigan governor who ran unsuccessfully for the Republican nomination in 1968.
Opinion polls suggest Mitt Romney is locked in an extremely close race with Barack Obama in November.
“I am honored that Americans across the country have given their support to my candidacy and I am humbled to have won enough delegates to become the Republican Party’s 2012 presidential nominee,” Mitt Romney said in statement.
As polls closed, the former Massachusetts governor was attending a fundraiser in Las Vegas with real estate tycoon Donald Trump.
He spent the day campaigning in Colorado and Nevada.
Ahead of Tuesday’s private fundraiser, the Obama campaign released a video focusing on Donald Trump’s comments falsely alleging that the president was born in Kenya.
The video seeks to draw a contrast between Mitt Romney and Senator John McCain, the 2008 Republican nominee, who once corrected a woman after she called Barack Obama a Muslim.
“Why won’t Mitt Romney do the same?” asks the clip.
On Monday, Mitt Romney stopped short of condemning Donald Trump’s comments.
“I don’t agree with all the people who support me. And my guess is they don’t all agree with everything I believe in,” Mitt Romney told reporters.
The Obama campaign video against Donald Trump is the latest in a series of attack ads.
On Monday, the Romney campaign released an attack ad criticizing Barack Obama over a federal loan to a solar panel maker which later went bankrupt.
On Tuesday Mitt Romney also met casino tycoon Sheldon Adelson, who gave millions to supporters of Newt Gingrich’s campaign during the primary season.
Experts say the outcome of November’s election could depend on what happens in a handful of battleground states, including Colorado and Nevada, as the candidates vie for the support of independent voters.
The next question of the campaign is who Mitt Romney will pick as his vice-presidential running mate.