Republican presidential hopeful Rick Santorum surprised observers by throwing only sporadic jabs at Mitt Romney in a major address Thursday at the Detroit Economic Club.

Santorum, vying for an upset victory in the Michigan primary on Feb. 28, drew some contrasts with Romney, but they were muted and overshadowed by a broader effort to connect economic issues to the social conservatism that has become his calling card.

Santorum affirmed his opposition to President Obama’s bailout of the auto industry — an unpopular stance in Detroit — and said his position was “more consistent” than Romney’s because he also opposed the federal rescue of Wall Street.