The billionaire was put on 1,238 delegates on Thursday
Donald Trump has reached the number of delegates needed to win the Republican nomination for US president, according to an AP count.
The billionaire was put on 1,238 delegates on Thursday after a small number of unbound GOP delegates told the news agency they would back him at the party convention in July.
With another 303 delegates at stake in five state primaries on June 7th, Mr Trump is expected to easily increase his total and avoid a contested convention in Cleveland.
Steve House, chairman of the Colorado Republican Party and an unbound delegate, said he liked the tycoon's background as a businessman.
He said: "Leadership is leadership. If he can surround himself with the political talent, I think he will be fine".
Oklahoma GOP chairwoman Pam Pollard added: "I think he has touched a part of our electorate that doesn't like where our country is. I have no problem supporting Mr Trump".
The Republican nomination race has often proved ugly, with party officials wary of Mr Trump's caustic style and provocative statements on Mexicans, women, building a wall between the US and Mexico and banning Muslims from the US.
But millions of grassroots activists, many outsiders to the political process, have backed his campaign as someone who is not afraid to offend people.
Mr Trump has spent just US$57m (€50.8m) on his campaign through the end of April. He covered most of that with at least US$43m (€38.3m) of his own money loaned to the campaign.
He also spent less than US$21m (€18.7m) on paid TV and radio commercials - around a quarter of that spent by Florida Governor Jeb Bush, who dropped out of the race three months ago.