NEWARK — President Obama swept into New Jersey on Sunday, pleading with his supporters to summon up the enthusiasm they poured into his election last November and deliver a victory for Gov. Jon S. Corzine.
“He’s one of the best partners I have in the White House. We work together,” Mr. Obama said. “We know our work is far from over.”
Mr. Obama’s appearances in Camden and Newark underscored the White House’s determination to stave off defeat for Mr. Corzine, the only Democratic incumbent up for re-election this year, who is facing an aggressive challenge from Christopher J. Christie, a Republican.
The race is one of several likely to be viewed as a barometer of the president’s popularity.
Virginia voters will also choose a new governor Tuesday, but there the Republican, Bob McDonnell, has a double-digit lead against the Democrat, R. Creigh Deeds, and the White House has all but conceded Mr. Deeds cannot overtake him.
In a Congressional race in upstate New York, the White House helped to engineer the surprise endorsement of the Democratic candidate, Bill Owens, by Assemblywoman Dede Scozzafava, the Republican nominee who dropped out on Saturday. The move by Ms. Scozzafava, a moderate former small-town mayor, only intensified the intraparty fighting in a contest that has become a battle for the future of the Republican Party.
In New York City, Mayor Michael R. Bloomberg and Comptroller William C. Thompson Jr. raced across the five boroughs in last-minute appeals to voters. Mr. Bloomberg tried to ward off complacency among his supporters, with polls showing him with a comfortable lead, while a vastly outspent Mr. Thompson tried to generate enthusiasm among core Democratic voters.
The New Jersey contest is attracting enormous attention, not only because of its closeness.
The sputtering economy here (unemployment is 9.8 percent) has helped to depress Mr. Corzine’s poll numbers and created uneasiness among Democrats nationally about a state they have carried in presidential contests since 1992. Republicans are likely to seize on a Corzine defeat as a sign that Mr. Obama’s policies are being rejected by the electorate, and argue that they will oust more endangered Democrats in 2010.
Most polls show the race too close to call; Mr. Obama’s visit to New Jersey on Sunday was his third to stump for Mr. Corzine.
Mr. Christie, undeterred by Mr. Obama’s appeal, barnstormed Sunday in Bergen County, the state’s most populous county, and in Republican strongholds like Morristown and Toms River. At a separate event in Morristown, Representative Joe Wilson, the South Carolina Republican who yelled “You lie!” at Mr. Obama on the House floor, campaigned for Mr. Christie.
“We need to get to the polls each and every person who is sick and tired of Corzine,” Mr. Christie said during an event at the historic Morristown Green.
On television talk shows on Sunday morning, some Democrats tried to play down the significance of Tuesday’s vote, suggesting that local issues and trends would eclipse national concerns. Top Obama advisers also said the campaigns, especially in New York’s 23rd District, suggested that Republicans were becoming too extreme.
“I think we’ve seen an interesting development over this weekend in a special election in upstate New York in a Congressional district,” David Axelrod said on “Face the Nation” on CBS. “The Republican candidate withdrew because of the strong third-party movement behind a very right-wing conservative.”
He added: “I think it sends a clear message to moderates within that party that there’s no room at the inn for them.”
In the upstate district, conservative activists nationally have rallied behind Douglas L. Hoffman, who will appear on the ballot on the Conservative Party line. Unlike Ms. Scozzafava, Mr. Hoffman opposes same-sex marriage and abortion rights.
A spokesman for Mr. Hoffman said Sunday that Ms. Scozzafava had revealed herself to be a Republican in name only by endorsing Mr. Owens, the Democratic candidate.
“This afternoon Dede Scozzafava betrayed the G.O.P.,” said Rob Ryan, senior communications adviser.
Meanwhile, Michael Steele, the national Republican Party chairman, boldly predicted victory for Republicans, saying voters were uneasy with Democratic policies on health care and the economy.
One wild card in New Jersey is the third-party candidacy of Christopher J. Daggett, who reached 20 percent in some polls last month, but has since fallen. It is not clear if people who have expressed support for Mr. Daggett will stay with him Tuesday or decide to back one of the major-party candidates.
Mr. Obama tried to rebut Mr. Christie’s attacks on the governor over the state’s economic problems, saying the Republican supported policies that contributed to the nation’s continuing financial woes.
“Listening to Jon’s opponent, you’d think New Jersey was the only state going through a tough time right now,” Mr. Obama said. “I have something to report: We have the worst financial crisis since the Great Depression. By the way, that didn’t start under Jon’s watch, that didn’t start on my watch.”
The message resonated with people like Deborah Howell, a receptionist who lost her job eight months ago. She attended the Newark rally, and said the city had been improving under Mr. Corzine. “It will get better if we keep it on the track it’s on now,” she said. “If they change it to Republicans, things’ll start going the other way.”
While the president urged his listeners to look past negative TV ads, Mr. Christie was aggressive on the stump, joking sharply about Mr. Corzine’s reliance on White House help.
He suggested that the governor, even if re-elected, would accept an ambassadorship rather than serve out a second term.
“He should go back to D.C. on Air Force One,” Mr. Christie told a raucous crowd in North Middletown in one of several stops he made Sunday on a weekend-long, 21-county bus tour
At the Park Ridge Diner at the northernmost exit of the Garden State Parkway, Mr. Christie shook hands with people like Judy Brendel, an education administrator from Montvale.
“I am against a long list of what Corzine stands for,” she said. “I’m very fearful of what’s happening in this country. I see young people, I see where they’re going, they don’t know what this country is about.”
As for her husband, John Brendel, 74, he said he was “anti-Corzine as much as I am pro-Christie.”Michael Barbaro, Colin Moynihan and Nate Schweber contributed reporting.