President Barack Obama raised a combined $43.6 million in April for his campaign and the Democratic Party, down from the month before, as he faces a Republican effort rallying around Mitt Romney for the White House. Obama's monthly fundraising haul fell short of the $53 million he raised in March. His campaign said more than 400,000 people contributed to the campaign last month, including 169,000 new donors. “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. Presidential campaigns and super PACs have until midnight Sunday to file their fundraising reports with the Federal Election Commission. The general election is in November. 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 GPS plans to open the 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 commercial will run in Colorado, Florida, Iowa, Michigan, North Carolina, New Hampshire, Nevada, Ohio, Pennsylvania and Virginia. This presidential race is playing out under dramatically looser campaign finance laws in the wake of a series of Supreme Court decisions that allowed independent groups to raise and spend unlimited donations as long as they don't coordinate directly with the campaigns they support. Strategists for the super PACs insist they are operating independently, but campaign finance watchdogs argue that the groups have effectively become high-dollar shadow campaign operations for candidates otherwise constrained by much stricter federal campaign finance rules. Several Republican-leaning groups spent millions to take control of the House and pick up six Senate seats in 2010.