"I have been dealing with a medical issue that is yet to be resolved," the 62-year-old Republican said in a statement Friday. "Although I am hopeful it will be resolved positively, it would not be fair to my constituents and supporters should I be forced to withdraw from the race midyear."
He offered no details on the medical condition. A spokesman did not immediately return calls.
There were no other Republicans in the race. Democrats must gain 15 seats to win a majority in the House.
The primary election for the Democratic nomination is June 6.
Gallegly, elected to Congress in 1986, represents most of Ventura County and parts of Santa Barbara County, northwest of Los Angeles.
The 10-term congressman won re-election in 2004 with more than 60 percent of the vote.
He serves on the House Judiciary, International Relations and Resources committees and is a member of the Permanent Select Committee on Intelligence.
|Sign up for our Daily Newsletter mailing list!|