Updated: 11:49 p.m. ET
(CBS News) Mitt Romney won all five Republican presidential primaries Tuesday night, completing a sweep of contests in New York, Connecticut, Rhode Island, Pennsylvania and Delaware.
Romney boasted more than 50 percent of the vote in all five states.
In Connecticut, with 91 percent of the expected votes in, Romney led Ron Paul 67 percent to 13 percent. In Rhode Island, with most of the expected votes counted, Romney led Paul 63 percent to 24 percent.
In Pennsylvania, with nearly all of the votes in, Romney had 58 percent. Rick Santorum, who dropped out of the Republican presidential contest earlier this month, followed with 18 percent of the vote.
Full primary result coverage
Romney is likely to add more than 200 delegates to the 692 estimated delegates he had already secured before the evening's five contests.
Romney will still lack the 1,144 delegates necessary to formally clinch the Republican nomination after Tuesday -- but the former Massachusetts governor is clearly claiming the mantle of presumptive Republican nominee. Even as he continues to put in the requisite work toward officially sealing up the Republican nomination, he pivoted to the general election in a speech Tuesday night in New Hampshire.
Speaking to supporters, the presumptive GOP nominee focused his attention solely on President Obama. Romney did not mention either of this remaining Republican rivals by name, instead casting himself as an improvement over the current president and promising "the start of a new and better chapter."
"A better America begins tonight," Romney told the enthusiastic crowd. "Tonight is the start of a new campaign to unite every American who knows in their heart that we can do better. The last few years have been the best that Barack Obama can do. But it's not the best America can do. Tonight is the beginning of the end of the disappointments of the Obama years."
The Obama campaign immediately hit back against the Romney camp, arguing in a statement that Romney's speech "should have been Back to the Future, because he has proposed a return to the same policies that got us into the economic crisis in the first place."Primary Results: Connecticut | Delaware | New York | Pennsylvania | Rhode Island
"Mitt Romney has spent the past year out on the campaign trail tearing down the President with a negative message that even Republicans who have endorsed him have criticized," Obama for America Press Secretary Ben LaBolt said in the statement. "This marks the end of that monologue. Now he must put his record and his agenda next to the President's."
Despite what increasingly looks like Romney's inevitable success in securing the Republican nomination, Newt Gingrich on Tuesday vowed to continue campaigning in North Carolina. He indicated , however, that he plans to reevaluate his run in the wake of his losses, and said Tuesday his campaign would in the coming days "look realistically where we're at."
The former speaker, who has only won two nominating contests, was counting on a strong performance in Delaware Tuesday to get a "bounce" that might prompt donors to take another look at his candidacy. He has vowed to stay in the race until the Republican presidential convention in Tampa this summer, but his presidential campaign is more than $4 million in debt and the pace of its fundraising has fallen significantly behind its spending, according to figures released by the campaign Friday evening.
Gingrich suggested that if Romney does clinch the nomination, he will support his candidacy.
"If he does end up as the nominee, I think every conservative in this country has to be committed to defeating Barack Obama," Gingrich said.
In an appearance on CNN Tuesday night, Santorum declined to explicitly endorse Romney, but said that "If he's the nominee, I'm going to do everything I can to make sure he defeats Barack Obama."
"Including endorse him?" asked CNN's Piers Morgan.
"Absolutely," Santorum responded.