"We just started our fundraising efforts in the last week of May and we are extremely pleased with the broad-based support in the last five weeks," said Steven Mnuchin, the Trump campaign's finance chairman.

His campaign committee took in $26 million, largely through email donation requests, while joint fundraising with the Republican National Committee added another $25 million. The Trump campaign had billed June as its first major fundraising month after it sustained its Republican primary efforts largely through loans from Trump himself.

Donald Trump and the Republican Party raised about $51 million in June as general election funding efforts ramped up, the Trump campaign said in a statement Wednesday.

General election fundraising marked an initial hurdle for the Trump campaign, which set up a donation infrastructure later than presidential candidates typically do. Trump's loans and a heavy dose of media coverage had allowed the campaign to get by with minimal fundraising during the primaries.

The campaign of Trump's presumptive Democratic opponent Hillary Clinton previously announced that it raised more than $40 million in June. Joint efforts with the Democratic Party added another $28 million, for a total of nearly $70 million.

For historical perspective, in June of 2012 Republican nominee Mitt Romney raised $106 million, outraising President Barack Obama by more than $30 million. Those figures also include joint fundraising with the candidates' parties and affiliated committees.



It remains to be seen how much cash the Trump campaign had on hand at the end of June. A Federal Election Commission filing later this month will give a glimpse into the campaign's spending habits.

It ended May with only $1.3 million on hand, versus more than $42 million for the Clinton campaign.

Previously, Trump had loaned his campaign about $45 million from his personal fortune, before announcing he would forgive the loans — effectively making a donation to his own campaign. However, as of last week Trump's campaign had declined to release the official paperwork and in the same week the FEC told NBC News no official paperwork forgiving the loans had been filed.

— CNBC's Ivan Levingston contributed to this report.