ABC News projected that Romney would defeat second-place Santorum in Maryland, in Wisconsin, and in Washington, D.C., where Santorum was not on the ballot.
Looking more inevitable than ever, Romney strode through the latest primary contests with a parade of establishment and revered GOP figures hoisting him up. His latest endorsements came from former President George H.W. Bush, budget idol Rep. Paul Ryan of Wisconsin and tea party scion Sen. Marco Rubio of Florida.
Already Romney had indicated that mentally, he'd moved on from the primary and on to the general election, after decidedly winning the primary in Illinois, a state in which Santorum's blue-collar appeal could have boosted him but didn't.
This week, the Republican National Committee -- which technically stays out of the primary until a nominee is decided -- announced it would start raising money jointly with the Romney campaign.
In Wisconsin, voters seemed to agree. Exit polls showed that regardless of their choice, 80 percent of them said they expected Romney to win the nomination, even as half of them said the former Massachusetts governor was "not conservative enough."
In a speech to supporters in Wisconsin, Romney, who has been dogged by charges that as a mega-millionaire he doesn't understand working-class values, planned to call President Obama disconnected.
"It's enough to make you think that years of flying around on Air Force One, surrounded by an adoring staff of true believers telling you what a great job you are doing, well, that might be enough to make you a little out of touch," he planned to say, according to excerpts of his speech.
Despite Romney's wins, Santorum showed no signs of leaving the race.
"We have now reached the point where it's halftime," he told his fans in Pennsylvania, his home state. "Half the delegates in this process have been selected. And who's ready to charge out of the locker room in Pennsylvania for a strong second half?"
Santorum also put his scorn for the mainstream GOP on center stage, jabbing at Romney again over the famous "Etch A Sketch" comment his adviser made and pushing back against the party's power brokers.
"Time and time again, the Republican establishment and aristocracy have shoved down the throats of the Republican Party and people across this country moderate Republicans, because, of course, we have to win by getting people in the middle," he said to cheers.
Romney won the majority of voters in many demographics, according to exit polls. For example, among the 40 percent of Maryland voters who said beating Obama was the most important characteristic for the eventual nominee, Romney won over 72 percent of them. He also won 65 percent of the vote among those who said experience is most important.
Romney's rivals have tried to block his seemingly unstoppable road to victory, pledging to stay in the race until the party's convention in August, in Tampa, Fla. By the rules of the Republican Party, the nominee must win 1,144 delegates, who are divvied up after each state primary; Romney is the only candidate who has a realistic path to get to that number, an argument that his campaign has made repeatedly.
Tonight's three victories extend Romney's lead even more. Most of Maryland's 37 delegates and Wisconsin's 39 are likely to go to Romney, and he'll get all of Washington's 16, too. Santorum didn't even qualify to be on the ballot in the District.
A figure that will stick out no matter how well Romney performs is the money that has been spent in his favor -- a dollar amount that Democrats are sure to say indicates that his appeal is artificial. For example, the Romney campaign and the super PAC supporting it have spent more than $3 million on TV ads in Wisconsin, four times as much as Santorum and his super PAC have spent.