Rep. Paul D. Ryan (R-Wis.), left, joins Mitt Romney in greeting people and… (Steven Senne, Associated…)
MILWAUKEE — Mitt Romney edged closer to capturing the Republican presidential nomination on Tuesday as he beat back a challenge from Rick Santorum in Wisconsin and swept the field in Maryland and the District of Columbia.
Santorum had counted on an improbable upset in Wisconsin to stop the party from coalescing, if reluctantly, around Romney, whose wins in the other two primaries were all but a foregone conclusion.
But with Romney and President Obama clashing anew Tuesday, Santorum was also fighting the widening perception that the race for the White House was transforming quickly into a two-man general election contest.
Romney is eager to turn that perception into reality after months of lurching between victories and losses in often messy party contests scattered across the country.
Helping him, oddly enough, is Obama. The president started airing a TV ad attacking Romney this week in six fall battleground states, underlining Obama's conclusion that his rival in November would be the former Massachusetts governor. (Obama's team also took on Romney in the perennial general election powerhouse of Florida on Tuesday, organizing a call with reporters to hammer Romney's plans for NASA as something that "would devastate Florida's Space Coast economy.")
Celebrating his victories in Milwaukee, Romney turned his sights, as he has on previous triumphant election nights, to the president. Citing a string of negative economic indicators — and laying the blame squarely on Obama — Romney told supporters, "When you drive home tonight and you stop by the gas station, just take a look at the prices and then ask yourself, four more years of that?"
Obama, he suggested, is "a little out of touch" after "years of flying around on Air Force One, surrounded by an adoring staff of true believers telling you that you're great and you're doing a great job."
Romney ignored Santorum, much as he had earlier in the day during a campaign stop at a fast-food joint in Waukesha, a suburb of Milwaukee.
Santorum, however, showed no sign of planning a quick exit. On Tuesday, he was raising money in Texas and gearing up for the April 24 primary in Pennsylvania, the state that he represented in Congress for 16 years.
Santorum gathered Tuesday night with supporters in Mars, Pa., to launch his three-week campaign for a comeback in the Pittsburgh steel region where he grew up. Minutes after the polls closed in Wisconsin, he told the crowd it was "halftime" in the chase for party nominating delegates.
"Who's ready to charge out of the locker room in Pennsylvania for a strong second half?" he asked.
Taking a shot at Romney for switching stands on issues, he called on voters to support "someone whose convictions are forged in steel, not on an Etch-A-Sketch."
Santorum's plan is fraught with peril. Pennsylvania ousted him from the Senate in 2006. Compounding that setback with a home-state loss to Romney would be a serious blow to his prospects for future races, should Santorum decide he wants to run for president again. By pressing further with his frequently brutal attacks on Romney's record, Santorum also risks antagonizing the growing ranks of Republicans who see his extended candidacy as helping Obama win reelection.
In a reminder that the party's battle against Obama is not yet fully joined, Romney too was headed to Pennsylvania — after a speech in Washington — to campaign outside Philadelphia on Wednesday at a spiral-staircase manufacturing plant. On the strength of the slashing advertising campaigns that have brought him victories in a host of similar states — Michigan, Ohio, Illinois — Romney hopes to finally dispatch his stubborn rival.
For Romney, it will take a deft touch to appeal to his party's conservative base in Pennsylvania without turning off moderates. That has proved to be a challenging task as he tangled with GOP rivals in some of the other general election battlegrounds, among them Iowa, New Hampshire, Florida, Nevada, Colorado and Wisconsin.
Up for grabs on Tuesday were 39 nominating delegates in Wisconsin, 37 in Maryland and 16 in the District of Columbia.
Santorum failed to qualify for the District of Columbia ballot. He also spent almost no time campaigning in Maryland, ceding the state to Romney.
But Santorum devoted more than a week to dashing around Wisconsin, stopping at bowling alleys and breweries to showcase his regular-guy credentials, all the while casting Romney as out of touch.
"We went out and showed, not only can we connect, but I can bowl!" Santorum told one crowd in Fond du Lac, noting his three-strike performance at Lakeshore Lanes in Sheboygan.
Romney took his own turn at connecting Tuesday by serving free submarine sandwiches to supporters at Cousins Subs in Waukesha. Dressed in jeans, with his sleeves rolled up, the smiling candidate offered customers a choice: ham-and-cheese or Italian. "What do you guys want to eat?" Romney asked.