The Chicago Sun-Times reported Wednesday that businessman Chris Kennedy (D) is planning to run for Senate in 2010.

The son of the late Sen. Robert F. Kennedy (D-N.Y.) has reportedly already filmed his first television commercial, and he signed on AKPD Message and Media as his media firm and Anzalone Liszt Research to do his polling.

Kennedy’s entrance into the race would appear to ensure that Democrats will have a primary fight for the seat currently held by appointed Sen. Roland Burris (D). State Treasurer Alexi Giannoulias (D) announced his candidacy earlier this year, raising more than $1 million for his bid right out of the gate.

And Kennedy isn’t likely to be the last Democrat to jump into the race: Burris has not decided yet whether he will run for a full term, and Rep. Jan Schakowsky (D) said she will decide about the Senate race next month.

Attorney General Lisa Madigan (D) also said she is considering the race; however, she has publicly stated that she is much more likely to run for governor in 2010. If Madigan ran for Senate, she would likely clear the Democratic field — and save the Democratic Senatorial Campaign Committee from a primary headache.

Among Republicans, Rep. Mark Kirk (Ill.) is strongly considering running for the nomination. Recent public polling showed Kirk in a very strong position against all of the Democrats except Madigan.