There’s some ugly trouble for Republicans out here in Southern California. Just days before the June 6 special election to replace jailed former Congressman Duke Cunningham, Senator John McCain has dumped the GOP candidate trying to succeed him.

McCain was slated to host a fundraising event on Wednesday for Brian Bilbray, the Republican candidate in the San Diego-area 50th Congressional District, left vacant after The Duke was hauled off to jail for accepting bribes.

But at the last minute, McCain pulled out citing differences with Bilbray over the immigration issue. Bilbray has dissed McCain’s immigration reform proposals as an unacceptable “amnesty.” Bilbray’s Democratic opponent by the way, Francine Busby, supports McCain’s plan.

“Senator McCain has canceled his appearance on behalf of Brian Bilbray to avoid distracting from the overall message of the Bilbray campaign,” Craig Goldman, executive director of McCain’s political action committee, said in a statement.

Right. McCain, who is a possible 2008 presidential contender, might also just want to keep his distance from the whole Duke stench. Latest polls show Bilbray in a very and unpredictable race. McCain’s withdrawl can’t be considered much of a boost, can it?