It’s not enough that he has the love of Julia Roberts in “America’s Sweethearts.” Now leading man John Cusack, 35, is the frontrunner in a Web campaign (albeit tongue in cheek) to put him in the White House. “The idea may seem silly at first, but on the other hand there are not many other compelling candidates out there,” said Dan Carol, a former Democratic Party political consultant whose group is behind putting Cusack in the White House. (For the record, former President Ronald Reagan began his career as an actor.) “From what we can tell,” Carol said of Cusack, he “is a good person, has strong progressive values and could make a good candidate.” Carol said some 200 people had volunteered to help organize a potential Cusack campaign in their cities since the idea was launched three months ago. Except now Cusack has competition — from his own sister, actress Joan Cusack, 39. “We like Joan a bunch,” Carol said on Wednesday. “She’s got the mettle to lead nations and the humility to not want the job.” A spokesman for John said that the actor was on vacation and not available for comment. No word from Joan.