Updated

Republican presidential hopeful and former Senator Rick Santorum raised a modest $582,000 in the 2nd quarter, the campaign reported Friday.

Santorum, an outspoken critic of President Obama and one of the most socially conservative candidates in the GOP field, raised $582,000 and has $229,000 remaining on hand, according to the report filed with the Federal Election Commission.

"In the short amount of time since Senator Santorum has been a candidate for president, he was able to raise a significant amount of resources," campaign finance director Amanda Kornegay said. "It is worth noting that Senator Santorum didn't hold his first official fundraiser until June 22, and between that day and June 30, he raised nearly half of the money he raised as an official presidential candidate."

That compares to the $18 million raised by former Massachusetts governor and presumed Republican frontrunner Mitt Romney in the past three months. Former Minnesota Governor Tim Pawlenty, who like Santorum polls in the bottom tier, raised $4.5 million.

President Obama raked in a combined $86 million for his campaign and the Democratic Party in the last three months, campaign manager Jim Messina announced Wednesday.

Santorum has spent months drumming up support in the early primary states of Iowa, New Hampshire, and South Carolina. Despite his low fundraising report, the campaign on Friday announced it would be expanding its field staff in Iowa.