Mitt Romney and Rick Santorum spoke to supporters after polls closed in Maryland, Washington, DC, and Wisconsin. Mitt Romney won all three contests.
Mitt Romney focused his speech in Milwaukee, Wisconsin, on President Obama in what is being seen as a turn towards the general election. The President "has spent the last four years laying the groundwork for a Government-centric society," he told supporters.
He said that he knew that free enterprise couldn't solve all of society's problems, but that "it can be a great force for good."
"The true engine of job creation in this country is the private sector," he said.
In Wisconsin, 42 delegates were up for grabs.
Mitt Romney was declared the winner of the Maryland primaries shortly after polls closed there at 8pm ET. Twenty-four of Maryland's 37 delegates are awarded on a winner-take-all by congressional district basis, with an additional 10 awarded to the overall winner of the state. Rick Santorum came in a distant second.
The 16 delegates in Washington, DC will all go to Mitt Romney, the winner in that contest. Rick Santorum was not on the ballot in Washington.
Rick Santorum spoke to supporters in his home state of Pennsylvania, telling them that "we've reached that point where it's halftime," referring to the fact that, after tonight, half of the delegates have been allocated. "Everyone deserves to be heard," he told the audience.
Pennsylvania holds its primary in three weeks, along with New York, Rhode Island, Connecticut and Delaware.