MADISON, Wis. -- It didn't take long for incumbent Democratic Gov. Jim Doyle to start attacking his Republican challenger about his stance on stem cell research in campaign ads.

In just the second television ad sponsored by Doyle's camp, a woman whose daughter has diabetes said that U.S. Rep. Mark Green's position on stem cell research is "too extreme." Doyle doesn't appear in the 30-second ad and his name is not spoken.

Green's campaign took issue with the ad slated to begin airing on Tuesday, saying it misrepresents Green's position on stem cells.

Green spokesman Rob Vernon said that a line in the ad saying that Green wants to outlaw stem cell research is false.

Doyle's spokesman Anson Kaye said that Green's record is clear that he wants to slam the door on stem cell research and shut it down.

Vernon said that Green only wants to stop an expansion of the embryonic stem cell research.