US Republican candidate Donald trump raised $51 million in June, dwarfing the $3.1 million raised in May, his organization says, addressing concerns that his campaign may lag behind in competition with Democratic candidate Hillary Clinton.

The organization reported Wednesday that Trump’s campaign for the 2016 vote had managed to take in $26 million, while joint efforts with the Republican National Committee in June and the last week of May brought in over $25 million.

The real estate tycoon, who frequently brags about self-funding his campaign to appear as an outsider in the US establishment, personally contributed an extra $3.8 million as well, not taken into account in the Wednesday announcement.

"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 for the Trump Campaign and Trump Victory," the campaign said in a statement.

The announcement came after US President Barack Obama infused new energy into the campaign of his former secretary of state.

“Hillary is steady. And Hillary is true. And she is in politics for the same reasons I am, because we can improve people’s lives through this work,” Obama said in Charlotte, North Carolina, on Tuesday.

Clinton has been busy ramping up her fundraising schedule; she managed to raise $68.5 million along with the Democratic Party in June.

The figure includes $40.5 that her campaign directly raised.

As a New Yorker businessman, Trump who is new to the US politics did not start holding fundraisers until late May.

The $51 million figure has a reassuring implication for Trump’s supporters as it could indicate that the reality TV star is capable of raising large amounts of cash to inject into his campaign,