Publicly, San Diego-area Republicans are rallying around Rep. Duke Cunningham (R-Calif.), the embattled Congressman who has been jolted in recent days by revelations that the FBI is investigating his close relationship with a prominent defense contractor.

And they reject suggestions that the former Vietnam War hero could face a primary challenge in 2006, or that anything now swirling will force Cunningham from office.

“Duke Cunningham served his country and served it well in Vietnam and in the U.S. Congress and definitely deserves the benefit of the doubt,” said Duane Dichiara, a veteran Republican consultant in Southern California.

But behind the scenes, several names of potential successors are already being tossed about, on the theory that Cunningham will decide not to seek a ninth term in 2006. The Congressman’s troubles are also providing Democrats a glimmer of hope in a district that gave President Bush 55 percent of the vote last year.

If Cunningham were to retire, most of the action would be in the Republican primary, where conservatives hold sway.

All but certain to run if Cunningham departs is former state Assemblyman Howard Kaloogian, who unsuccessfully sought the GOP Senate nomination in 2004.

“I think it’s premature to talk about, and I hope Duke stays,” Kaloogian said. “But I have made it plain that if Duke decides he is done with the seat, I’d be interested in it.”

Kaloogian has plenty of bona fides in the conservative movement. In 2003, he was a leader in the successful campaign to recall then-California Gov. Gray Davis (D). And he is the co-chairman of a nonprofit organization called Move America Forward, whose mission is to defeat terrorism and support American troops. The group’s current campaigns involve rallying support for John Bolton, the nominee to be U.S. ambassador to the United Nations, and sending gourmet coffee to the troops in Iraq and Afghanistan.

Kaloogian has already earned the support of Steve Baldwin, the executive director of the powerful Council for National Policy and a former San Diego-area state assemblyman — who has also been mentioned as a possible candidate for the Cunningham seat.

“Howard’s my man in that race,” Baldwin said.

Other possible Republican candidates, according to GOP sources, include San Diego County Supervisor Bill Horn, state Sen. Bill Morrow, state Assemblyman George Plescia, San Diego County Supervisor Pam Slater-Price, state Assemblyman Mark Wyland and California Consumer Affairs Department Director Charlene Zettel, a former assemblywoman.

How many of them would actually run — if the opportunity arose — is hard to say.

Horn and Morrow both live in the adjoining 49th district, a seat held by Rep. Darrell Issa (R-Calif.). But both live close enough to the 50th, and have enough overlapping territory in their districts, to plausibly seek the Cunningham seat.

Morrow was the runner-up to Issa in the 2000 GOP primary, and both he and Horn took steps to run for the seat in 2003, when it appeared as if Issa would run for governor in the recall election. Morrow still has a Congressional campaign account open, though it only had $9,400 in it as of March 31.

Of the other potential candidates, Wyland is new to the Legislature and may not be ready for a House bid, Plescia is running for the state Senate though could change course and Slater-Price and Zettel may be too moderate for a Republican primary electorate. Still, if Zettel — the first Latina Republican elected to the California Legislature — were to get public support from Schwarzenegger, that could make a difference.

In a possible preview of what a primary would be like, Kaloogian displayed a willingness to throw elbows at all of the other possible candidates.

“I’ve demonstrated that I can accomplish more out of office than any of these people can in office,” he said.

Meanwhile, Democrats appear to be coalescing around their 2004 nominee, college professor Francine Busby. Busby, who took just 37 percent of the vote to Cunningham’s 58 percent last year, said that national and local Democrats — along with independents and moderate Republicans — are suddenly showing a keen interest in her candidacy.

“We are ready to take advantage of the fact that there’s going to be a competitive race this time,” she said.

Busby, who spent $212,000 on the 2004 race compared to Cunningham’s $940,000, said the scandal surrounding the Congressman has enabled her to upgrade her fundraising targets for this cycle. Before the revelations about Cunningham’s deals with the defense contractor, she hoped to raise $300,000 by the end of the year; now the target is $500,000 to $1 million.

“Our goals are changing daily,” she said.

And Busby rejected the conventional argument that her best chance for winning is if a wounded Cunningham seeks another term; she said she could benefit from a bloody open Republican primary. Democrats, meanwhile, appear unified, and most of the party leaders from the San Diego area — including Reps. Bob Filner (D-Calif.) and Susan Davis (D-Calif.) are expected to endorse Busby on Thursday.

But local analysts do not rule out the possibility that a wealthy political novice from either party could jump into the race. Dichiara, for his part, laughed at the suggestion that the Democrats can be competitive in the 50th.

“Let them spend all the money in the world here,” he said.