The Republicans are itching for a fight on their nuclear option, but some of the groups who are most offended by the effort are conservative activist groups. The AP's Jesse J. Holland reports:

Two groups normally allied with Republicans have bolted from the party's effort to ban judicial filibusters — the first major defections from a conservative push to prevent Senate Democrats from blocking President Bush's judicial nominees.

The National Right to Work Committee, a 2.2 million-member group critical of unions, and the Gun Owners of America, with 300,000 members, say they fear eliminating judicial filibusters could eventually lead to doing away with filibusters altogether.

Both groups have benefited in the past from use of the Senate parliamentary tactic to block gun control and labor bills. A filibuster technically is unlimited debate, and requires 60 votes from the 100-member Senate to stop.

For the GOP to eventually be successful in changing the Senate's two century old rules, almost the entire Republican caucus will have to be in line. With conservative activist groups breathing down the necks of Majority Leader Frist and Majority Whip McConnell, it might be just a little more difficult for the Republicans to trample dissent.