Mitt Romney clinches GOP nomination with Texas win (+video)

Read more: Barack Obama's lead in California stays solid, poll shows

Read more: Polls show Barack Obama leads marginally in three crucial states

Read more: Battleground states: The road to 270 electoral votes to win the presidency

Read more: The 2012 Veepstakes: 20 possible VP picks for Mitt Romney

WASHINGTON — Mitt Romney clinched the Republican presidential nomination Tuesday with a win in the Texas primary, a triumph of endurance for a candidate who came up short four years ago and had to fight hard this year as voters flirted with a carousel of GOP rivals.

According to The Associated Press count, Romney surpassed the 1,144 delegates needed to win the nomination by winning at least 97 delegates in the Texas primary.

The former Massachusetts governor has reached the nomination milestone with a steady message of concern about the U.S. economy, a campaign organization that dwarfed those of his GOP foes and a fundraising operation second only to that of his Democratic opponent in the general election, President Barack Obama.

Romney would be the first Mormon nominated by a major party. His religion has been less of an issue than it was during his failed bid four years ago.

"We did it!" Romney proclaimed in a message to supporters, noting that "it's only the beginning."

"An honor and a privilege and a great responsibility," Romney told supporters at a fundraiser in Las Vegas. "And I know the road to 1,144 was long and hard, but I also know that the road to 11-06 — Nov. 6th — is also going to be long and it's going to be hard and it's going to be worth it because we're going to take back the White House and get America right again."

Romney must now fire up conservatives who still doubt him while persuading swing voters that he can do a better job fixing the nation's struggling economy than Obama. In Obama, he faces a well-funded candidate with a proven campaign team in an election that will be heavily influenced by the economy.

Romney's campaign went on the attack Tuesday, releasing a Web video citing the Obama administration's loan-guarantee investments in four renewable-energy firms that lost money and laid off workers.

The message — "President Obama is fundamentally hostile to job creators" — has been a theme of the Romney campaign since he launched his presidential bid. But sensing an opportunity to reach a new audience, the campaign planned to highlight Obama's support for the failed renewable energy company Solyndra, among other private ventures the Obama administration helped support.

"We need to have presidents who understand how this economy works," Romney told reporters Tuesday. "Sometimes I just don't think he understands what it takes to help people. I know he wants to help, but he doesn't know what he's got to do."

Romney's message and his big day, however, were somewhat overshadowed by real estate mogul Donald Trump and his discredited suggestions that Obama wasn't born in the United States.

Romney spent Tuesday evening at a Las Vegas fundraiser with Trump, who had toyed with the idea of running for president. Romney says he believes Obama was born in America but has yet to condemn Trump's repeated insinuations to the contrary.

"If Mitt Romney lacks the backbone to stand up to a charlatan like Donald Trump because he's so concerned about lining his campaign's pockets, what does that say about the kind of president he would be?" Obama's deputy campaign manager, Stephanie Cutter, said in a statement.