WASHINGTON — President Barack Obama raised a combined $43.6 million in April for his campaign and the Democratic Party as he faces a unifying Republican effort around Mitt Romney for the White House.

Obama's monthly fundraising haul fell short of the $53 million he raised in March, but he remains far ahead of Romney in cash on hand. The president also pulled in about $15 million at a Hollywood fundraising event this month.

"This election is going to be close, given the historic challenges this country faced when the president came into office," campaign manager Jim Messina told supporters in a YouTube video released Wednesday. The campaign said it added 169,000 new donors to its rolls last month.

Obama's fundraising announcement came the same day the Republican group Crossroads GPS said it would spend $25 million on ads critical of the president. Crossroads is the non-profit arm of American Crossroads, a "super" political committee backed by former George W. Bush adviser Karl Rove that has raised about $100 million this election to defeat Obama.

Crossroads plans to open its effort Thursday with an $8 million TV ad that castigates Obama on the economy, by far the biggest issue this election year. The 60-second TV spot will run in Colorado, Florida, Iowa, Michigan, North Carolina, New Hampshire, Nevada, Ohio, Pennsylvania and Virginia.

This presidential race is playing out under remarkably looser campaign finance laws in the wake of federal court decisions that allow independent groups to raise and spend unlimited donations as long as they don't coordinate directly with the campaigns they support.

Messina's message pointed to the millions of dollars being spent on anti-Obama ads by so-called special interests and oil company executives – specifically citing the Koch brothers, who founded Americans For Prosperity. That group has spent about $5 million on ads so far critical of Obama.

While Romney and the Republicans have super PACs working in their favor, so does Obama. Priorities USA Action on Tuesday released a video critical of Bain Capital, the firm Romney once headed. But Democratic super PACs have raised and spent less on average than their GOP counterparts, including Restore Our Future, which supports Romney.

Obama's campaign and the Democratic Party had about $124 million cash on hand at the end of March, while Romney and the GOP reported $43 million left in the bank at the end of March, federal reports show.

Presidential campaigns and super PACs have until midnight Sunday to file their fundraising reports with the Federal Election Commission.

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