Mitt Romney is one step closer toward winning the GOP presidential nomination after sweeping the field in Wisconsin, Maryland and Washington, D.C.
In Wisconsin, many residents said 'electability' was the number one factor in deciding their vote.
Romney gained ground among voters who've kept their distance in the past. He lost the evangelical vote by only 3 percent. But he won the Tea Party vote over rival Rick Santorum.
The former Massachusetts governor now leads the race with 655 delegates. That means he has more than half of the 1,144 delegates needed to win the GOP nomination for president.
But even before his latest wins, Romney was already in general election campaign mode, stepping up his attacks on President Obama.
"Under this president's watch, more Americans have lost their jobs than during any other period since the Depression," Romney said in Milwaukee.
"When you drive home tonight and stop at a gas station, just take a look at the prices and ask yourself, 'Four more years?'" he said.
President Obama is sharpening his attacks as well, taking Romney on in television ads and on the campaign trail.
"I can't remember a time when the choice between competing visions of our future has been so unambiguously clear," Obama said.
After Romney's three-state win, political observers say the GOP primary race is over.
Unfazed, Santorum has vowed to fight on.
"There are no marching bands. We're hitting the field. The clock starts tonight," the former Pennsylvania senator told supporters at an election night party outside Pittsburgh.
Former House Speaker Newt Gingrich is also hanging on, saying he has no plans to leave the race. He's promised to stay on the campaign trail until the GOP convention in Tampa, Fla., Aug. 27-30.
"The Republican Party never abandons the timeless conservative principles," he declared.
Meanwhile, Romney is focusing on Pennsylvania, Santorum's home turf, as he looks to close the deal for the Republican nomination.