US billionaire and gay marriage opponent Donald Trump has announced he will not run for the Republican presidential nomination.

In a statement today, he said he had a “strong conviction” that he could win the race and ultimately the presidency in 2012 but is not ready to leave the private sector.

Trump said: “After considerable deliberation and reflection, I have decided not to pursue the office of the Presidency. This decision does not come easily or without regret; especially when my potential candidacy continues to be validated by ranking at the top of the Republican contenders in polls across the country. I maintain the strong conviction that if I were to run, I would be able to win the primary and ultimately, the general election.

“I have spent the past several months unofficially campaigning and recognise that running for public office cannot be done half heartedly. Ultimately, however, business is my greatest passion and I am not ready to leave the private sector.”

The thrice-married entrepreneur had angered gay rights campaigners with a series of remarks on gay marriage.

He said in March that he was against gay marriage and civil benefits for gay couples.

Trump also said that the denial of rights to gay and lesbian couples was not a “big problem”.

“I’m against it,” Trump said. “I just don’t feel good about it, I don’t feel right about it. I’m against it.”

“And I take a lot of heat because I come from New York. You know for New York it’s like, ‘How can you be against gay marriage?’ But I’m opposed to gay marriage.”

In today’s statement, he thanked his “millions of supporters” and pledged to continue speaking out on issues he champions, such as job creation.