President Obama’s re-election campaign is again trying to raise money by highlighting the fact GOP challenger Mitt Romney is now winning the fundraising battle.

“I will be outspent,” starts an email sent to supporters and signed by Obama. “I will be the first president in modern history to be outspent in his re-election campaign, if things continue as they have so far.”

Last month, Romney and Republicans out-raised Obama and Democrats for the first time -- $76.8 million, compared to $60 million.

The loss prompted Obama 2012 campaign manager Jim Messina to write, “For the first time in this campaign, we got beat in fundraising. … We knew this moment would come when Romney secured the nomination. What happens next is up to you. Help close the gap right now."

David Heller, president of the Democratic strategy firm Main Street Communications, said the letters convey the true sense of urgency within the campaign.

“Everybody understands this race is really, really close,” he told FoxNews.com “And if the Obama campaign is going to win, this is going to be about fundraising.”

The letter sent Tuesday by the president makes clear that he’s not referring to the well-known fact that conservative-leaning super PACs and anonymous outside groups are also outpacing similar liberal-leaning groups.

“I'm talking about the Romney campaign itself,” writes the president. “Those outside groups just add even more to the underlying problem.”

The president said the situation can be explained by simple math: His side raised almost three-quarters of its money from donors giving less than $1,000, while Romney's campaign raised more than three-quarters of its money from individuals giving $1,000 or more.

“We can be outspent and still win,” the president continued. “But we can't be outspent 10 to 1 and still win."

The president has spent a considerable amount of time fundraising, having attended 32 events this month and more than a 100 so far this year.