(CNN) - There is more evidence Wednesday that with 20 days until the November election, the battle for New Jersey's top job is a dead heat.
Forty percent of New Jersey likely voters questioned in a new Quinnipiac University poll say they back Democratic incumbent Jon Corzine, with 41 percent supporting Republican challenger Chris Christie. According to the survey, 12 percent say they'll vote for independent candidate Christopher Daggett.
Christie, the former federal prosecutor in New Jersey, held a four point lead over Corzine in Quinnipiac's poll from two weeks ago, with Daggett at 12 percent.
Two other surveys out over the last week, a Fairleigh Dickinson University Public Mind poll and Monmouth University/Gannett New Jersey survey, also indicated that the New Jersey gubernatorial contest was all tied up.
The new Quinnipiac poll suggests that 76 percent of Democrats back Corzine, 83 percent of Republicans support Christie, and independents back Christie 45 to 32 percent, with 16 percent supporting Daggett.
"Daggett appears to take slightly more voters from Christie than from Corzine," says CNN Polling Director Keating Holland. "It's not a big margin, but in a tight race, every little bit might count. If Daggett's support drops between now and election day, Christie may be the likely beneficiary."
According to the survey, the vast majority of Corzine and Christie backers say their minds are made up, but less than four in ten Daggett supporters say they won't change their mind.
"It's still a nail-biter. Christopher Christie has never given up the lead, but it's been getting slimmer and now it's a dead heat," says Maurice Carroll, director of the Quinnipiac University Polling Institute. "Historically, third party candidates fade on election day. Apparently, voters agree. Very few of his backers are committed to independent candidate Christopher Daggett and 77 percent of all voters say he has no chance of winning."
The Quinnipiac University poll was conducted October 7-12, with 1,264 New Jersey likely voters questioned by telephone. The survey's sampling error is plus or minus 2.8 percentage points.