Savoring their victories in gubernatorial contests in New Jersey and Virginia, Republicans were trying on Wednesday to build momentum, in a time of economic concern, for a strong challenge to President Barack Obama's party in next year's midterm congressional elections.

The White House insisted that the Republican victories in the two races for governor were not referendums on Obama but rather the reflections of "very local issues that didn't involve the president," as Robert Gibbs, the chief administration spokesman, told reporters.

Michael Steele, the Republican national chairman, was jubilant at a Wednesday morning news conference in Washington. "As recently as a couple of months ago, Republicans were written off," Steele said. "Many of you were writing our epitaph and reminiscing of the good old days, whatever they happened to have been."

The "real heroes" of Tuesday's victories, Steele said, were "the Republicans and independents and, yes, even Democrats who spoke up against an incredibly arrogant government in Washington that has put our country, our freedoms and our economy at risk with unprecedented spending."

Rep. Eric Cantor of Virginia, the Republican whip, took a similar tack. "I think that the victories last night here and in New Jersey indicate that when Republicans stand united, we can win, whether it's in a Northern state or a Southern state, and we can appeal to the independent voters," Cantor said Wednesday morning on Fox News. "What's important to take out of these elections is that voters in both states were very concerned about the direction of the economy and rejected out of hand the economic policies being pursued by the White House and Speaker (Nancy) Pelosi."

As they assessed the results, Democratic lawmakers and party strategists said it was their judgment that voters remained uneasy about the economy, and did not see Democrats delivering on the health, energy and national security changes they promised a year ago when they strengthened their hold on Congress and won the White House.

"Most of us ran on that," said Rep. Gerry Connolly of Virginia, president of the Democrats' freshmen class in Congress. "We must deliver."

At the White House on Wednesday morning, Gibbs said it was hardly news that people are concerned about the economy. "I don't think the president needed an election or an exit poll to come to that conclusion," Gibbs said.

Local issues were dominant concerns in both of the gubernatorial races, exit polls indicated, and the results seemed to carry cautions for both parties. Still, a collective frustration with the economy and anxiety over high property taxes helped Republicans regain some ground they had ceded to Democrats in recent years.

Democrats, meanwhile, took heart from a closely watched congressional race in upstate New York, where a Democrat who received a late push from the White House exploited division among Republicans to defeat a Conservative Party candidate who had attracted national backers like Rush Limbaugh and Sarah Palin, the former Alaska governor.

In New Jersey, Chris Christie, a former federal prosecutor, became the first Republican to win statewide in 12 years by vowing to attack the state's fiscal woes with the same aggressiveness he used to convict corrupt politicians.

He overcame a huge Democratic voter registration advantage and a relentless barrage of negative commercials to defeat Jon Corzine, an unpopular incumbent who outspent him by more than 2-to-1 and drew heavily on political help from the White House, including three visits from Obama.

With 98 percent of precincts reporting, Christie had 49 percent of the vote, Corzine 44 percent.

In Virginia, where Obama was the first Democratic presidential nominee to carry the state since 1964, Robert McDonnell, a Republican and former state attorney general, rolled to victory over Creigh Deeds, a veteran state senator.

With 99 percent of precincts reporting, McDonnell had 59 percent and Deeds 41 percent. McDonnell's victory, along with Republican victories in the races for attorney general and lieutenant governor, ended eight years of Democratic control in Richmond.