The first poll out on the Chicago mayor's race shows there's no early favorite for what will be the first open-seat contest in the city in decades.

Leading the way were the 35 percent of voters who didn't have a candidate preference in the Democratic primary. And no one among the nine potential candidates included in the poll registered a statistically significant advantage.

Longtime mayor Richard Daley (D) announced Tuesday that he will not seek reelection next year.

For what it's worth, Cook County Sheriff Tom Dart led the way with 12 percent support. He was followed by state Sen. James Meeks with 10 percent and Rep. Luis Gutierrez with 9 percent.

Rep. Jesse Jackson Jr. garnered 8 percent in the poll and White House Chief of Staff Rahm Emanuel received 7 percent.

The poll, commissioned by the Chicago Sun-Times, was conducted by the firm McKeon and Associates. It surveyed 600 registered voters and has a margin of error of plus or minus 4.3 percentage points.

The primary isn't until February of next year, but the race is already heating up and Emanuel is expected to make a decision soon on whether to leave the White House for a run at city hall.

On CNN Thursday, Jackson took an early shot at Emanuel, warning that if President Obama's chief of staff did decide to get in the race, "it will become a national campaign."

"The president's record will probably be brought into that campaign," said Jackson, who noted "Rahm Emanuel will have to answer the questions about those communities that have been left behind."

Like Emanuel, Jackson has not yet made a decision on a mayoral run.

Earlier this week, President Obama said Emanuel would be "an excellent mayor," but said he didn't expect his chief of staff to make any decision before the November midterm elections.