Rick Santorum is stepping into Mitt Romney's old backyard to talk about his own economic views, a direct challenge to the Republican front-runner.

The former Pennsylvania senator is set Thursday to address the
Detroit Economic Club, just 23 miles from where Romney went to high
school. Now surging in national polls, Santorum is showing a growing confidence in what should be safe territory for the longtime GOP front-runner.

Romney not only grew up in Michigan, he is the son of a former
governor. And his family members have been deeply involved in state
politics for decades.

Despite the inherent advantages for his rival, Santorum has
vowed to plant the flag in Michigan, which hosts a presidential primary on Feb. 28.