Spill petition being circulated in caucus A LEADERSHIP spill is looking more likely with supporters of Kevin Rudd reportedly circulating a caucus petition to force a challenge to Prime Minister Julia Gillard. There are also reports that a ballot could be held at 9am on Thursday. Mr Rudd is under pressure from his caucus supporters to make a move in the dying days of the current parliament ahead of the September 14 election. Any move against Ms Gillard will first require a petition, signed by at least a third of the caucus, for a special meeting. A separate ballot would be required for a leadership spill. If a spill occurs, independent Tony Windsor says he won't rule out switching to the coalition if there is any leadership change. The problem is that noone is driving the bus. Mr Katter, who has formed his own party to contest the September 14 election, said his decision to back Mr Rudd would be in "the nation's interest" and he did not want to "condemn Australia to a landslide election" win for the coalition. Shadow Treasurer Joe Hockey attacked Mr Katter's decision. Bob Katter shouldn't be propping up an awful Labor Govt. They are a circus and continue to focus on their own jobs rather than Aussie jobs," Mr Hockey tweeted. The Australian Greens, whose sole MP in the lower house is deputy leader Adam Bandt, have flagged they would not support the opposition. "The only people who can determine confidence are the parliament of Australia or the people," she told reporters in Canberra on Wednesday. We are saying we will do nothing to facilitate Tony Abbott getting into the prime minister's position. Backers of the prime minister have challenged him to make the move. The ball's in Mr Rudd's court. The prime minister is not going to stand down," cabinet minister Greg Combet said earlier on Wednesday. In March, Mr Rudd refused to stand after Ms Gillard called a leadership spill.