TURNBERRY, Scotland (Reuters) - U.S. Republican presidential candidate Donald Trump, stung by a meager fundraising haul compared with that of Democratic rival Hillary Clinton, predicted on Friday his campaign would draw "staggering" numbers this summer.

Supporters have voiced concern he will not have enough money to finance his campaign for the Nov. 8 presidential election. Trump had $1.3 million in cash to start the month, compared with rival Democrat Hillary Clinton's $42 million war chest.

"The numbers are going to be, I think, quite staggering, especially in July," Trump, a New York real estate developer, said at a news conference in Turnberry, Scotland, where he reopened a golf resort.

He said he had only begun fundraising in earnest a few weeks ago and that the numbers, especially for small donations, had been "amazing."

Steve Mnuchin, Trump's top fundraiser, told CNBC on Thursday that in the past week the campaign had raised about $10 million together with the Republican Party at fundraising events. He said Trump also raised $6 million through online donations. [L1N19F0VD]

Trump said on Friday the July report "will show you some pretty massive numbers." Trump also has suggested he could use more of his personal wealth to help win the White House.

(Reporting by Doina Chiacu in Washington; Editing by Howard Goller)