(CNN) - With less than two months until primary day in Illinois, a new poll suggests that Democrat Alexi Giannoulias and Republican Mark Kirk are their party's frontrunners in the battle for President Barack Obama's old senate seat - though the Chicago Tribune/WGN survey also indicates that more than a third of Democratic voters and nearly half of Republican voters are undecided.
Thirty-one percent of likely Democratic primary voters questioned in the poll say they're backing Giannoulias, who was elected in 2006 at age 30 as Illinois state treasurer. That's 14 points ahead of former Chicago Urban League President Cheryle Jackson.
No other Democratic candidate was in double digits, according to the survey, which also indicates that 35 percent of Democrats remain undecided.
According to the poll, Giannoulias leads Jackson among female voters by a two-to-one margin, even though Jackson's the only woman in the Democratic primary.
The survey also indicates Kirk, a five term congressman from suburban Chicago, has the support of 41 percent of likely Republican primary voters. No other GOP candidate breaks double digits in the poll. But 46 percent of Republican voters say they're undecided.
The Senate seat up for grabs next year was once held by Barack Obama. Sen. Roland Burris, the controversial appointment by then-Gov. Rod Blagojevich, still fills the seat. Burris said earlier this summer that he will not run for a full term next year.
The Chicago Tribune/WGN poll was conducted December 2-8, with 600 likely Democratic primary voters and 600 likely Republican primary voters questioned by telephone. The survey's sampling error is plus or minus 4 percentage points.
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