Democrats running for governor in New Jersey and Virginia face possible defeat in November, despite strong showings by President Barack Obama in those states last year, in elections that could render the first judgments on the Obama presidency.
New Jersey Governor Jon Corzine, a close Obama ally, is struggling to win re-election in the face of a strong challenge by Republican Christopher Christie.
The Obama administration has turned out in support of Corzine, a wealthy former Goldman Sachs executive.
At a rally in Atlantic City this week, Vice President Joe Biden said it was "critically important" that Corzine is re-elected.
The Corzine campaign adapted the popular Obama slogan, hanging a banner next to Biden reading: "Yes we can -- again.
In Virginia, the only other U.S. state with a gubernatorial contest this year, Democrat Creigh Deeds has been losing so much ground in the polls to Republican Bob McDonnell that he has blamed the Obama administration's $787 billion economic stimulus plan for his low popularity.
A Washington Post poll published on Friday gave McDonnell a commanding lead of 53 percent to 44 percent, with less than a month to go until election day.
"Frankly, a lot of what's going on in Washington has made it very tough," Deeds told Politico newspaper. "We had a very tough August because people were just uncomfortable with the spending."
The Virginia race, where incumbent Democratic Governor Tim Kaine cannot run because of term limits, is more likely to be decided on national issues such as the economy and healthcare, said Larry Sabato, director of the Center for Politics at the University of Virginia.
A recent survey showed many voters in Virginia, where Obama won by 6 percentage points, expect taxes to rise as a result of a U.S. healthcare overhaul being considered in Congress.
Biden campaigned for Deeds this week in Virginia and the Democratic National Committee allocated another $1 million for his campaign. Democrats were waiting to see if Obama would make another appearance on Deeds' behalf.
The race in heavily Democratic New Jersey reflects more the struggles of an unpopular incumbent than the national political mood, and will be decided on Corzine's handling of such issues as the state's high property taxes, analysts said.
Corzine has lagged in polls, sometimes by double digits, for months in a state that Obama won by 15 points and where the legislature is controlled by Democrats. The race has tightened up in recent weeks.
Corzine has tried to link Christie, a former U.S. Attorney with a successful record prosecuting corrupt public officials and suspected terrorists, to former President George W. Bush, whose market deregulation Corzine blames for the nation's financial crisis.