The GOP presidential front-runner, after pulling off a three-primary sweep Tuesday night, made his strategy for the coming weeks fairly clear.
On the stump, he will increasingly focus on the incumbent president. His latest campaign web video also engaged Obama directly over gas prices and energy policy.
But the campaign and its supporters will be pouring resources into Pennsylvania, in a determined bid to deny Santorum a win in the state he represented in Congress and potentially push him out of the race.
Romney, speaking to a group of newspaper editors Wednesday in Washington, D.C., said his rivals are free to make their own decisions but that "I hope we are able to resolve our nomination process as soon as possible."
Romney was heading next for a rally in Pennsylvania. The campaign has already set two more events for Thursday in the state, including a visit to his Pennsylvania headquarters in Harrisburg.
The campaign plans to move more people into that operation in anticipation of a grueling battle ahead of the April 24 primary. Meanwhile, the Romney-supporting Restore Our Future super PAC bought $240,000 in ad time this week for Pennsylvania and the other four states holding primaries in late April. The super PAC spent the same amount last week.
If Romney can best Santorum on his home turf, it will make Santorum's path forward almost impossibly narrow.
"We have to win here," Santorum said Wednesday.
Santorum spokesman Hogan Gidley also said Tuesday night that the Pennsylvania race is "pivotal."
"You could survive it, but it would be tough," Gidley said, speculating about the implications of a Pennsylvania loss.
Gidley, echoing his boss' remarks, said a victory in Pennsylvania would give the campaign "momentum" going into May -- when more conservative-leaning states seen to be more favorable to Santorum are set to vote.
Santorum on Tuesday hammered the point that only half the total delegates available in the GOP contest have been awarded, and predicted the Pennsylvania contest could turn the tide.
"Who's ready to charge out of the locker room in Pennsylvania for a strong second half?" he asked.
Santorum, who held his rally in Pennsylvania, was plugging away Wednesday with three more events scheduled across the state -- at a gas station, a bowling alley and a repair shop.
He's highlighting his Pennsylvania roots and urging primary voters there to give his campaign the boost it needs to justify continuing into May.
The delegate math, though, is beyond daunting.
It takes 1,144 to win, and Romney has blown past the halfway mark with his wins on Tuesday.
In his victory speech, Romney declined to mention his GOP competitors and kept his remarks Obama-focused.
He mapped out in stark terms what appeared to be his general election message. He portrayed Obama as an enemy of business, himself as its promoter. He portrayed Obama as the steward of a "government-centered society," himself as the champion of a revitalized "opportunity society."
In the most memorable line of the night, Romney accused "out-of-touch liberals like Barack Obama" of saying they want a strong economy while showing they "don't like" business.
"It's a bit like saying you like an omelette, but you don't like eggs," Romney said. He said Obama's vision would lead to high unemployment, "crushing debt" and "stagnant wages."