(Image Credit: Mark Wilson/Getty Images)

DETROIT- Stumping in Mitt Romney's home state, Rick Santorum took the opportunity to rebut his primary rival's super PAC ads, tout his own conservative credentials and consistency, and say that he believes the auto industry would have recovered without the bailout.

"Now I know you folks here in Michigan have been hearing some things on the television from one of my opponents that I am a big spender," the former Pennsylvania senator, currently rising in the polls, told the Detroit Economic Club.

"I was the most conservative senator, by far, based on the state I represented and the spending record I had," Santorum said, touting a study mentioned in the Weekly Standard that rated him as more conservative than "just about everybody but four, and those four folks happened to represent states like Oklahoma and Wyoming."

The pro-Romney super PAC "Restore Our Future" launched an ad Wednesday in Michigan calling Santorum a "big spender" and a "Washington insider."  Santorum used most of his speech to re-hash his jobs and economic plan and also contrasted his record with the former Massachusetts governor. Santorum said he would make sure to care for both the homeless and "those on the very margins of our society, the very poor."

"We have a president who says that he supports the Occupiers who divide America between 99 and one, and another candidate in this race that suggested that he didn't care about the very poor, he cared about the 95 percent," Santorum said referring to Romney without mentioning his name. "How about a candidate who cares about 100 percent? Who cares about everybody and gives them the opportunity to rise in society?"

The former Pennsylvania senator is referring to a comment Romney made on CNN earlier this month when he said he wasn't concerned with the "very poor" because they have an "ample safety net." Romney has said he misspoke.

Santorum's campaign used the same populist theme in a fundraising e-mail sent Thursday: "American families are struggling," the e-mail reads. "Our jobs are being sent overseas. And the massive debt is robbing our children of the future they deserve. And according to news accounts, where was Mitt Romney caught yesterday? With Donald Trump, at a New York law firm specializing in profiting off bankruptcies."

Despite the venue - Michigan has been one of the states hit the hardest by the economic downturn - Santorum still spoke about social issues, linking them to a healthy economy. "We certainly won't be able to have limited government, lower taxes if the family continues to disintegrate."

During a Q&A, Santorum was asked if he supported the 2009 auto bailouts (the big Detroit three are currently experiencing record profits).

"Governor Romney supported the bailout of Wall Street and decided not to support the bailout of Detroit," Santorum answered. "My feeling was that … the government should not be involved in bailouts, period. I think that's a much more consistent position." Attempting to make the point that Romney is playing politics with the issue, Santorum added that Romney supported the bailout of the financial industry (TARP, the Troubled Asset Relief Program) because it was done during the Bush administration and was against the auto bailout because it came under President Obama's time in office.

Santorum stressed he was against both. "If we had just stayed out of it completely and let the market work, I believe the market would have worked," he said. "Why? Because markets would have had to react and do what was necessary to structure it to be competitive."

The Romney campaign has also been trying to paint Santorum as supportive of labor unions. They sent out a research e-mail Thursday titled "Rick Santorum: Big Labor's Favorite Senator."

During the address, Santorum again pushed his blue-collar roots, mentioning his grandfather's work as a coalminer, saying he is sure that "his grandson running as a conservative Republican [has] caused quite a few flips in the grave for him," and he has " no problem with private sector unions."

But, he added, "I don't feel quite as warm and fuzzy about public sector unions. I think public sector unions are in an intrinsically unfair bargaining position because the people sitting across the table from them, unlike the business person who has shareholders, or themselves who have money on the line, or both, the public employee unions are sitting across from someone who it's not their money. And it's not their tax dollars that's by and large gonna pay for these things."

As he left the event, he told a reporter he doesn't know why Romney is going after him on unions in Michigan, adding he's "not hostile to labor unions."