Mitt Romney made a leap toward winning the Republican presidential nomination with a clean sweep of Wisconsin and two other primaries on Tuesday that handed a heavy defeat to main rival Rick Santorum.
TV networks projected that Romney won easily in Wisconsin, Maryland and Washington, D.C., in a major boost for his effort to become the Republican who will face President Barack Obama in the November 6 general election.
Senior Republicans will now likely increase their calls for the party to rally behind Romney, despite deep reservations among many conservatives about whether he is one of them.
The defeats for the conservative Santorum ramps up pressure on him to pull out of his increasingly bitter standoff with the former Massachusetts governor Romney.
In his victory speech in Milwaukee, Romney took aim at Obama over his handling of the U.S. economy and high gasoline prices.
"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," Romney will say, according to speech excerpts released by his campaign.
Obama mentioned Romney's name in a speech on Tuesday, signaling that the White House now sees the millionaire former executive as effectively the Republican nominee.
He mocked Romney for backing a Republican budget plan authored by a key ally backer in Wisconsin, Congressman Paul Ryan.
Obama's sharp partisan tone, and Romney's swift and withering response, foreshadowed the campaign battles to come.
"He said that he's very supportive of this new budget and he even called it 'marvelous,' which is a word you don't often hear when it comes to describing a budget," Obama said.
Romney came from behind in the last couple of weeks to surge to the top of the polls in Wisconsin, and the loss further diminished former U.S. senator Santorum's hopes of a miracle finish to wrestle the nomination from his more moderate opponent.
Romney is now likely to have well over half of the 1,144 delegated needed to clinch the nomination at the Republican convention in August.
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