The man who nearly defeated Rep. Gary MillerGary Gene MillerTwo lawmakers propose first House bipartisan Ex-Im bill New Dodd-Frank fix runs risk of Lehman-esque meltdown It's official: Dem squeaks through in key California House primary MORE (R-Calif.) in 2012 won't run again even though Miller is retiring.

Former California state Sen. Bob Dutton (R), who made it into a runoff election with Miller last cycle and won 45 percent of the vote in the fall, tells the Riverside Press-Enterprise that he's committed to running for local office instead.

San Bernardino City Councilman John Valdivia (R) will run, however, giving Republicans a candidate in the race. California State Assembly candidate Paul Chabot (R) and Fontana Mayor Acquanetta Warren (R) also haven't ruled out bids.

Democrats are still likely to pick up the seat that President Obama won by a 16-point margin last election, though the all-party primary will be even more contested with Miller now out. 

Redlands Mayor Pete AguilarPeter (Pete) Ray AguilarGOP revolts multiply against retiring Ryan Pelosi: Discharge petition won't promote Trump's wall Pelosi: GOP discharge-petition holdouts helping Ryan ‘save face’ MORE (D) has the Democratic Congressional Campaign Committee's backing, while attorney Eloise Gomez Reyes (D) has support from EMILY's List. Former Rep. Joe Baca (D-Calif.) is also running, though he's struggled to raise any money for the race.

Miller, who was facing an uphill battle for reelection, announced earlier this week that he would retire at the end of his term.

Dutton and Miller, both Republicans, faced off in the general election last fall because of a quirk in California's election law. The top two candidates advance through the primary no matter what their party is, and a crowded field of Democrats kept Aguilar slightly below the two Republicans in 2012, costing Democrats a likely pickup.

That's unlikely to happen again this year unless the GOP can find two — and exactly two — candidates who can draw serious support.