After a flurry of surprise retirements, GOP Rep. Howard “Buck” McKeon’s announcement was one of the worst-kept secrets of the last year. So even though the district is competitive, Republicans weren’t caught off guard and have two credible candidates already in the race.

The California congressman’s exit has been rumored for a long time. Jon Fleischman of the California-based Flash Report reported last April that McKeon was telling people that he may retire.

With that expectation, two prominent local Republicans are running: state Sen. Steve Knight, whose legislative district overlaps significantly with the congressional district, and former state Sen. Tony Strickland, who ran unsuccessfully in the neighboring 26th District last cycle. Strickland lost to Democrat Julia Brownley, 53 percent to 47 percent, in a more Democratic district.

Three Democrats are running, including podiatrist Lee Rogers, who lost to McKeon, 55 percent to 45 percent, in 2012. After that credible run, Democratic strategists had been giving Rogers a longer look. But other candidates may choose to get into the race now that it is officially open.

Even though the initial Republican field looks to be at least a tier better than the Democratic side, there are a couple of factors that could make this a takeover opportunity.

At the presidential level, the district is competitive. Mitt Romney carried it, 50 percent to 48 percent, in 2012, and Barack Obama carried it, 51 percent to 49 percent, four years earlier. Going back to 2004, President George W. Bush won it by a wider 59 percent to 41 percent.

California’s top-two primary system throws a bit of uncertainty into the race. But until the candidate field solidifies, it’s unclear whether it will be a factor at all. The filing deadline for the race is March 7.

For now, we’re changing our Rothenberg Political Report/CQ Roll Call rating of California’s 25th District to Republican Favored from Safe Republican and wait to see if it becomes a more serious contest.