It's all economy, all the time for Romney DETROIT (AP) - Days before a pivotal primary, Mitt Romney is highlighting his economic plan in what was billed as a major campaign speech delivered at a cavernous and largely empty football stadium. Romney's speech repeated new tax proposals he released earlier this week, including lowering marginal individual tax rates by 20 percent. He offered few new policy ideas, though he did offer new details on how he would raise the retirement age to help keep Social Security solvent. The Detroit Economic Club hosted the speech at Ford Field, where the Detroit Lions play football. The crowd occupied just a portion of the field itself, and the tens of thousands of stadium seats sat empty. Romney is fighting an unexpectedly stiff challenge in his home state of Michigan from former Pennsylvania Sen. Rick Santorum, where voters go to the polls Tuesday. It's all economy all the time for Mitt Romney, who's back to campaign basics as he tries to fend off Republican presidential rival Rick Santorum in Michigan and Arizona primaries next week. The former Massachusetts governor courted tea party voters in suburban Detroit on Thursday night with an indictment of President Barack Obama as a man who is "comfortable living with trillion-dollar deficits." A day earlier, in Chandler, Ariz., he called for a 20 percent cut in personal income tax rates, a step he said would help the economy grow and create jobs. Next up is a speech before the Detroit Economic Club, in a city that is struggling and a state where unemployment stood at 9.3 percent in December. He was pulled into a discussion of social issues earlier in the week in Michigan, and again at a debate in Mesa, Ariz., on Tuesday with Santorum, Newt Gingrich and Ron Paul. But his remarks to the tea party audience in Milford were devoted to the economy. "The highest priority is making sure we get on a track to a balanced budget," he said, adding that he would eliminate some programs and cut others, and make sure his proposed across-the-board tax cut didn't interfere with plans to eliminate red ink. Opinion polls show voters aligned with the tea party are more likely to support Santorum than Romney, and the former Massachusetts governor went out of his way to praise them as part of his courtship. I appreciate your willingness to get out of your homes," he said. By pre-arrangement, Romney agreed to answer audience questions that had been given in advance to the event's emcee, and nearly all of them related to the economy. But he sidestepped one, when he was asked how he would respond to Obama in a campaign debate next fall if the president pointed out similarities between the health law that Romney pushed through the legislature in Massachusetts, and the version Congress approved. That was an invitation to discuss a requirement for all residents to purchase insurance, a feature that conservatives loathe in Obama's health care bill but is also present in the Massachusetts law. Romney steered clear. Instead, he said: "The first thing I'd say to him is, `You say you copied (the Massachusetts law), how come you didn't give me a call? I'd have told you what worked, what did not work.' He added that the federal law was too expensive, raised taxes and cut $500 billion from Medicare over a decade. While he drew applause for his remarks, it wasn't clear how much support he picked up. "I am an undecided voter," said Mary Ann Cherasaro, a tea party member and retired bookkeeper from Troy.. She said she liked what Romney had to say but wasn't ready to choose between him and Santorum. She said she probably wouldn't make up her mind until primary day. Her husband, Nick Cherasaro, said he was considering voting for Romney, Santorum or Gingrich. After listening to the former Massachusetts governor, Cherasaro said: "He knows what has to get done. He knows how to do it. The thing we've got to do is get rid of Obama.