"We are all ready to move past this dark cloud of scandal," Campa-Najjar said by telephone. "I look forward to restoring some integrity and dignity to this district."
Issa, who represented the neighboring 49th District over 18 years before deciding not to seek reelection last year, said Hunter faced a difficult decision between defending himself in court and protecting his family from testimony that he cheated on his wife -- and paid for affairs with donor funds.
"The reality is Duncan made a mistake," Issa said by phone. "Reaching for the campaign credit card in what clearly is a personal expense is inappropriate. It was certainly bad judgment and not reimbursing it much earlier was a mistake."
Issa said voters should remember there were "two Duncan Hunters" -- one who joined the Marines after the Sept. 11 attacks and defended veterans in Congress for a decade-plus, and one who veered from his marriage and made improper campaign spending decisions.
DeMaio said Hunter did the right thing.
"While this must have been a difficult decision for him, Congressman Hunter's decision to plead guilty is the right one for his family and his constituents and shows that no one should be above the law -- especially members of Congress," DeMaio said by phone.
While Hunter's main political rivals did their best not to focus on how the guilty plea might improve their election chances, political experts were not so reluctant.
"This gives the Republicans a much stronger chance of holding on to a critical seat," University of California, San Diego political scientist Thad Kousser said. "They lose the advantage of incumbency and name-brand, but getting away from the scandal and the soap opera this has become will allow the party to focus on issues that are popular to voters in this district."
San Diego State political science professor Brian Adams also said Republicans are much more likely to retain the seat with Hunter off the ballot.
"I think the Democrats' best chance was a Campa-Najjar/Hunter matchup," he said. "I think DeMaio, Issa or Jones all match up well against Campa-Najjar."