Gov. Bob McDonnell (R) returns Monday from San Diego, where he attended a seminar and fundraiser this weekend sponsored by the Koch brothers, the billionares who support conservative causes.

Gov. Bob McDonnell greets students attending Boy's State after he spoke to them on the final day at Liberty University June 22 in Lynchburg. (AP Photo/News & Daily Advance, Jill Nance)

The location and other details are generally kept under wraps, though they leak out. McDonnell’s attendance was listed on his weekly political schedule.

Democratic activists held a demonstration in downtown San Diego Sunday to protest the event, according to local news reports.

McDonnell has gone to previous Koch brother seminars, including one last summer in Vail. He traveled to San Diego from Park City, Utah, where he attended an event Saturday organized by presidential hopeful Mitt Romney.