Democrats and Republicans made their final campaign push Monday ahead of closely watched elections in three states, with the White House carefully targeting its resources in a bid to head off Republican victories. 

Vice President Joe Biden joined Democratic candidate Bill Owens, who is running against third-party Conservative Party candidate Doug Hoffman in an upstate New York congressional election.

It became a two-man race over the weekend when Republican candidate Dede Scozzafava dropped out. Scozzafava, who was criticized as too moderate by members of her own party, endorsed Owens on Sunday. But it's unclear how much of an impact that endorsement will have in the conservative district, as many of her supporters are expected to drift toward Hoffman.

The seat from New York's 23rd congressional district became open when President Obama named Republican Rep. John McHugh, who had served the district for nine terms, to be secretary of the Army.

Biden, at a rally Monday morning, lambasted the "Bush-era" policies of Owens' opponent, saying Hoffman wants to "emulate" the Bush administration's agenda -- which Biden said "brought this country to its economic knees."

Singling out former Vice President Dick Cheney and conservative radio talk show host Rush Limbaugh, Biden criticized Republicans for what he described as an unwillingness to tolerate differing views within their own party.

Biden touted Owens as a "pragmatic and tough" candidate who is strong on national defense and tax relief.

"We do not want to go back to the failed Bush economic agenda and ideological approach to government," Owens said at the rally, adding that his opponent advocates a clear "partisan agenda."

Meanwhile, Obama headlined two rallies for New Jersey Gov. Jon Corzine on Sunday, and Republican challenger Chris Cristie did the same, both candidates pushing to drive up voter turnout in what the polls show is a dead-heat election. 

Christie dropped by a get-out-the-vote rally Sunday evening in Republican-heavy Toms River. A crowd of some 400 chanted his name and cheered when he promised to give Corzine a pink slip on Tuesday. Christie was continuing to tour the state by bus. 

The New Jersey race is a statistical tie. The latest state poll out of Quinnipiac University shows Christie with a 2-point lead over Corzine, but that spread is within the margin of error. 

In the last days of a bitter race featuring merciless ads and deep divisions over tax policy, both candidates are more focused on getting their supporters to the polls than on wooing undecided voters. 

"You need to work hard on Tuesday," Obama told a Camden crowd Sunday. "I need you to go back into your neighborhood. I'm going to need you to knock on doors. ... I'm going to need you to do the same thing you did last year." 

Democrats, though, appear to be bracing for a loss in Virginia, where Democratic candidate Creigh Deeds has consistently trailed Republican Bob McDonnell. McDonnell is holding a pair of rallies in Virginia Monday, in Alexandria and Richmond, while Deeds continues to campaign. The Democrat will join outgoing Gov. Tim Kaine, who cannot run for re-election, for a get-out-the-vote rally at Virginia Commonwealth University. 

The status of these three races has raised questions about the power of Obama's coattails -- in Virginia, Deeds is trailing even though Obama remains relatively popular. And Democrats are mindful of the possibility that a string of losses for the party could be viewed as a referendum on Obama's first nine months in office, or as a harbinger of the 2010 congressional races. 

The New Jersey race is considered the Democrats' best chance to hold on to a seat. 

The Associated Press contributed to this report.