Presidential hopeful Rick Santorum sought to draw another sharp contrast between himself and Republican rival Mitt Romney when his campaign released four years of tax returns Wednesday night.

The documents, reported by Politico, show Santorum and his wife, Karen, earned more than $3.5 million from 2007 through 2010, but paid more than one-quarter of their earnings back in taxes. The most they paid in taxes was in 2010, when they earned $923,411 and paid an effective tax rate of over 28 percent.

Romney's 2010 tax returns show the former Massachusetts governor and wife Ann earned $27 million and paid a tax rate of 13.9 percent.

"I felt very successful in making money.  Also, I was very successful in paying taxes," Santorum told CNN on Wednesday. "I think our tax rates were ... between 25 percent and 28 percent.  You know, I do my own taxes and maybe I didn't have all the deductions and exclusions that I could have. But I was trying to be as straightforward as I could and paying the taxes I thought I owed."

New Gingrich's 2010 tax records, however, show he paid even more than Santorum in taxes, earning $3.1 million that year and paying back 31.5 percent.

The Santorums filed an adjusted gross income of $659,637 in 2007, that rose to $945,100 in 2008, $1.1 million in 2009 and $923,411 in 2010.

'We've been very blessed'
While the candidate acknowledged his success, Santorum was quick to point out that he has two children in college, a special needs child and a home that has lost 40 percent of its value.

"I took a lot of that money and actually paid down a rather significant mortgage to the point where ... my mortgage was still below the value of my house," he said. "And that's been a bit of a hit for us. And I have two kids in college and a child with a disability and needing care, so, you know, we've had some expenses and we've been very blessed to have the opportunity to be able to handle those and still be in the black.

The release does show the former Pennsylvania senator's wealth grew since he lost his re-election bid in 2006.  The latest Republican to surge in the polls has disputed the notion he has cashed in from his time on Capitol Hill.

But shortly after the information was made public, Santorum sought to use it to play up the blue-collar background he speaks about so frequently on the campaign trail. 

He referred to himself as a "grunt lawyer" in a Pittsburgh law firm before getting to Congress.

Santorum took a break from stumping in Florida last month before the Sunshine State's primary to return home to ready the documents that he himself files each year, never relying on an accountant.

He also points to his re-election loss as an opportunity for him to gain private-sector experience, something Romney has critiqued Santorum for not having.

"In many respects, I have to say the people of Pennsylvania didn't always give me what I wanted, but they gave me what I needed.  And in retrospect, Piers, it was probably the best thing that ever happened to get away from Washington to give me a perspective on things," he told CNN's Piers Morgan.

"It was a really great opportunity to get a whole bunch of different life experiences in the private sector and I think it's made me a better candidate coming forward here for president," Santorum added.

Four years worth of tax returns is the most any GOP presidential hopeful has released.  Ron Paul now becomes the only candidate who has yet to make his returns public.