The only state voting this week where the outcome is doubtful is Delaware. Romney's 5-state sweep

Mitt Romney swept all five Republican primary elections Tuesday night, putting an end once and for all to any hopes for a comeback by his beleaguered GOP primary opponents.

The last state to be called was New York, where voting ended at 9 p.m.; Romney was previously projected the winner in Connecticut, Rhode Island, Delaware and Pennsylvania.


There was little suspense in tonight’s elections. Only in Delaware, where Newt Gingrich camped out in recent days and collected endorsements from top local officials, was Romney at any risk of losing. Even a Gingrich victory there would have been unlikely to complicate Romney’s glide to the Republican convention in Tampa.

( Also on POLITICO: GOP delegate tracker)

But with nearly all of the vote reported, Romney was crushing Gingrich in Delaware by a 30-percentage-point margin. Speaking to supporters in Manchester, N.H., Romney declared a formal end to the primary season and predicted: “Together, we are going to win on Nov. 6.”

“After 43 primaries and caucuses, many long days and more than a few long nights, I can say with confidence and gratitude that you have given me a great honor and solemn responsibility,” he said, framing the general election as a test of the country’s economic resilience.

Said Romney: “The last few years have been the best that Barack Obama can do. But it’s not the best America can do.”

Romney has not yet secured enough delegates to clinch the GOP nomination officially, but he has already been treated by his party as its presumptive nominee for two weeks, since Rick Santorum ended his White House bid earlier this month.

Now, with an imposing delegate lead over his Republican opponents and virtually every party leader calling for a pivot to the general election, there’s no longer any doubt that Romney is in position to claim the Republican nomination.

Whether Romney’s remaining opponents — Gingrich and Ron Paul — take the hint following the evening’s returns is unclear.

In his election-night remarks, Gingrich said it was time for him to “think carefully about how we can be the most helpful to the country” in a possible hint that he might re-evaluate his campaign. But he also emphasized that he has nearly two dozen upcoming events scheduled in North Carolina, which doesn’t hold its primary until May 8.

In a sign that Team Gingrich hopes to stay in the race past this week, his campaign released a video earlier in the day rallying support for a same-sex marriage ban on the North Carolina ballot the same day as the presidential primary.

Paul, meanwhile, has consistently said that he will stay in the race until the Republican convention this summer, despite not having won a single primary or caucus. In a Monday interview with CNBC, Paul said again that he has no plans to exit the race.

“You want to see how you do. And who knows? Maybe somebody will stumble,” Paul said.

That “hey-you-never-know” attitude neatly sums up the level of competition in the Republican primary at this point: even conservatives who have opposed Romney or expressed skepticism about him as President Barack Obama’s rival have generally accepted that Romney will be their nominee.

For Romney, that means the most serious task facing him in the coming days is raising money and growing his operation to keep pace with the much larger Obama campaign. The most recent campaign finance reports showed Obama with more than $100 million on hand — a 10-to-1 advantage over Romney.

That gap may close quickly, however, as Republican donors who have remained neutral so far open up their wallets for the GOP standard-bearer. And for the first time, Romney is starting to benefit from the ability to raise money jointly with the Republican National Committee.

Romney has also been aided by Republican outside groups that are already spending millions on TV ads against Obama. American Crossroads began a new ad campaign against Obama this month and the American Future Fund, another independent pro-GOP group, on Tuesday launched a $2 million ad campaign in eight swing states.

He has also begun to take sharper incoming fire from the Chicago-based Obama campaign, which released a statement ahead of Romney’s remarks Tuesday accusing him of making “dishonest attacks” against the Democratic incumbent.

“When the president took office, we were losing 750,000 jobs a month because of the failed Bush policies — policies that Mitt Romney would bring back if elected,” Obama spokeswoman Lis Smith said. “Mitt Romney may have an aversion to the truth, but he can’t change the facts of the president’s record.”

Romney has yet to collect an endorsement from Santorum, the onetime extreme underdog who turned out to be his most formidable Republican competitor. In a Tuesday night CNN appearance, Santorum tiptoed to the edge of saying he was ready to support his former rival.

“It’s very clear he’s going to be the Republican nominee,” Santorum said. “I’m going to be for the Republican nominee.”

Santorum adviser John Brabender told POLITICO ahead of Tuesday’s elections that his former candidate won’t explicitly throw his support to Romney before they have the chance to meet and talk at length.

“Look, the senator takes his endorsement very seriously. He feels there’s many things for he and Gov. Romney to talk about. This isn’t just a five-minute meeting: How do you do, let’s endorse,” Brabender said.

MJ Lee, Mackenzie Weinger and Juana Summers contributed to this report.