(YAHOO! NEWS) — Mitt Romney began Tuesday night with an easy primary victory in Maryland, but his fate in Wisconsin–the biggest contest of the evening–remains unknown.

The Maryland race was called for Romney as the polls closed at 8 p.m ET. In D.C., which Romney is also expected to win Tuesday, Santorum did not appear on the ballot. Together, Maryland and the District have 53 delegates up for grabs. But Wisconsin–which will award 42 delegates–remains the major wild card and holds the potential to change the course of the primary race. Polls close in Wisconsin at 9 p.m. ET.

Wisconsin is a swing state that will factor heavily in the 2012 general election. If Santorum is able to best current delegate frontrunner Romney there, it could significantly boost Santorum’s campaign going forward.

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