Mitt Romney cruised to primary victories in Pennsylvania and four other Northeastern states Tuesday against a shrunken field of challengers, cementing his status as the presumed Republican nominee against President Obama in the fall.

Romney sought to frame the contest as a referendum on whether Americans are better off now than they were four years ago, arguing that most are not, in a prime-time speech in New Hampshire.

"It's still about the economy, and we're not stupid," Romney said.

Most of the remaining drama drained from the GOP presidential race two weeks ago after Rick Santorum dropped his campaign, concerned that he was headed for a loss in Pennsylvania, the state he had represented for 16 years as a House member and then as a member of the U.S. Senate. Santorum was the strongest remaining threat to Romney, drawing a coalition of skeptical conservatives in a bid to stop the former Massachusetts governor.

Republican primary voters also went to the polls in Delaware, New York, Connecticut, and Rhode Island. At stake were a total 209 delegates to the national nominating convention in Tampa, Fla.

Pennsylvania could have been an intriguing battle. Santorum grew up there, and two other candidates still in the race were born in the state: former House Speaker Newt Gingrich (Harrisburg) and libertarian-minded Texas U.S. Rep. Ron Paul (Pittsburgh).

Gingrich, his campaign nearly broke, concentrated his efforts in Delaware, which was to award all 17 delegates to the winner. He had said he would "reassess" his campaign if he did not do well there - and Romney beat him there by a 2-1 ratio.

Paul has a committed base of supporters and enough money to keep campaigning. He told CNBC on Tuesday that he would press on to the convention, seeking to have as many delegates as possible. "You don't quit because you happen to be behind," he said. "You want to see how you do. And who knows? Maybe somebody will stumble."

Santorum has yet to endorse the likely nominee, though he came close Tuesday night on Piers Morgan's show on CNN. "It's very clear that he's going to be the Republican nominee, and I'm going to be for the Republican nominee," Santorum said. He also said Romney's speech "set the right tone."

As the votes were counted Tuesday, Romney spoke in Manchester, N.H., near where he had launched his second campaign for the GOP nomination last summer. He used much of the occasion to offer a rejoinder to Obama's main campaign theme: that the president and Democrats are guarantors of "fairness" for working Americans while the GOP is about continued tax breaks for the wealthy.

"I see children even more successful than their parents - some successful even beyond their wildest dreams - and others congratulating them for their achievement, not attacking them for it," Romney said.

"This America is fundamentally fair. We will stop the unfairness of urban children being denied access to the good schools of their choice; the unfairness of politicians giving taxpayer money to their friends' businesses; the unfairness of requiring union workers to contribute to politicians not of their choosing; the unfairness of government workers getting better pay and benefits than the taxpayers they serve; and we will stop the unfairness of one generation passing larger and larger debts on to the next."

Obama, too, was on a general-election footing Tuesday, campaigning at the University of North Carolina in Chapel Hill. He stressed his push to have Congress renew the Stafford student loan program for college students, preventing a doubling in its interest rates. Republicans in Congress are opposing renewal of the lower rates.

"College education is one of the best investments America can make for our future," Obama said. "We can't price most Americans out of a college education. We can't make higher education a luxury. It's an economic imperative."

In Pennsylvania, plenty of Obama's supporters turned out despite their candidate's being unopposed on the Democratic ballot. At the Langhorne-Middletown Fire Co.'s north station, Patricia Wall, 67, of Langhorne, said she voted for Obama "because he thinks things through clearly, and he's a man of his word. I know a lot of people blame him for the economy, but it's not his fault."

Though Romney faced no real remaining opposition in Pennsylvania, he campaigned Sunday in Franklin County and held events in Pittsburgh and the Philadelphia suburbs on Monday.

Analysts were looking at how large a slice of the popular vote Santorum might get in Pennsylvania for clues as to whether Romney was continuing to have trouble winning over evangelical Christians and other social conservatives in the GOP base.

Santorum ended up with about one vote in five - and in the end, it may not matter much, analysts said. After all, in a Pew Research Center poll released last week, 88 percent of Republicans who supported someone other than Romney for the nomination said they would vote for him in November against Obama.

Nancy Redeker, leaving a polling place at the Gladwyne firehouse in Montgomery County, said she voted enthusiastically for Romney and will support him in the fall.

"I'm very concerned about the economy," Redeker said. "Obviously, Obama is a very likable person, but I don't think he's very experienced, and it's showing in mistakes he's made." She added, "I don't want my grandchildren inheriting an enormous amount of debt."

Pennsylvania has voted for the Democrat for president in five straight elections. George H.W. Bush was the last Republican to carry the state, in 1988, narrowly edging Michael Dukakis.

Still, it has been close several times and analysts expect Pennsylvania to be a target once again. Recent polls by Quinnipiac University and by Franklin and Marshall College have the state's voters giving low marks to Obama for his handling of the economy, and about half of those surveyed say it's time for a change in the White House. Said Franklin and Marshall pollster Terry Madonna: "It's not going to be an easy deal here for either side by any stretch."

Contact Thomas Fitzgerald at 215-854-2718 or tfitzgerald@phillynews.com or on Twitter @tomfitzgerald. Read his blog, "The Big Tent," at www.philly.com/bigtent.

Joshua Fernandez contributed to this article.