By Emily Cadei, CQ Staff

The Democratic presidential primary is starting to take a financial toll on Barack Obama , the latest fundraising numbers show. The Obama campaign spent more than it raised in April, a first in 2008, as it sought to knock off New York Sen. Hillary Rodham Clinton by pouring money into the Pennsylvania, Indiana and North Carolina primaries.

Presumed Republican presidential nominee John McCain , meanwhile, had his best fundraising month yet, and dumped the majority of his receipts into his fattening bank account.

Obama continued to demonstrate his fundraising prowess, leading the way among the three candidates with $32 million in receipts last month, according to the campaign’s latest report with the Federal Election Commission. The Illinois senator continued to use his successful funding formula, raising the overwhelming majority of his contributions from small donors who gave $200 or less.

His campaign also reported 200,000 new donors in April.

But Obama spent $36.4 million over the course of the month — about $4 million more than he raised during the same time — as he tried to sew up the nomination. Despite outspending Clinton in Pennsylvania and Indiana, he lost both contests.

As Obama and Clinton continue their primary fight, McCain is starting to accelerate his own fundraising, although he remains at a huge financial disadvantage compared to the Democratic candidates. The Arizona senator raised $18.5 million in April, up from $15.4 million in March. And since wrapping up his nomination, McCain has been able to minimize his expenses — disbursing only $8.4 million last month — as he consolidates party support for the fall campaign.

Thanks to the headway made with Republican donors, McCain was able to up his cash on hand to $21.8 million, from $11.6 million at the end of March. McCain, however, still trails well behind the Obama, who had $37.3 million on hand at the end of April.

Clinton continued to raise money in April as well, even as her prospects of winning the nomination receded. She reported $21.9 million in contributions. In addition, Clinton loaned herself $5 million from her personal funds, doubling to $10 million the amount she has now invested in her campaign. The campaign is now carrying an overall debt of $19.5 million. Clinton reported having $6 million in cash to spend on the remaining primaries.