Democrats got a boost they desperately wanted when GOP House Foreign Relations Chair Rep. Ed Royce announced his retirement from California's 39th CD. Royce has held the northern Orange County seat easily since 1992, in part because he's built a deep relationship with immigrant communities in a district that is 29 percent Asian and just 31 percent white. But without Royce, Republicans will struggle to hold the seat.

The 39th District encompasses upscale Fullerton and Yorba Linda in Orange County, Diamond Bar in Los Angeles County and Chino Hills in San Bernardino County. In 2012 it voted for GOP nominee Mitt Romney 51 percent to 47 percent. But in 2016, as Donald Trump struggled with the non-white and college-educated voters who dominate the 39th, Hillary Clinton carried it 51 percent to 43 percent.

With President Trump's approval rating languishing south of 40 percent, a Republican lacking Royce's reputation and $3.5 million would be a considerable underdog in November, particularly without a competitive GOP candidate for governor or senator to drive out turnout.

However, if Republicans do have a chance to hold this seat, it probably rests with the state's top-two primary system. Before today, Royce had five announced Democratic opponents with over $100,000 in the bank. If they split the vote enough ways and only two name-brand Republican run, the Republicans could theoretically win both general election slots in the June top-two primary and shut Democrats out of the seat.

Of the Democrats, insurance businessman Andy Thorburn led the money chase in October thanks to a $2 million personal loan, followed by pediatrician Mai-Khanh Tran and philanthropist/former lottery winner Gil Cisneros. The field also includes former Cal State Fullerton professor Phil Janowicz and attorney Sam Jammal. But if one doesn't break out of the pack, it would heighten the risk Democrats could get shut out.

Republicans do have a deep bench of potential candidates in this district including former Royce staffer Young Kim (who lost her Assembly seat last year and is currently running for Orange County Supervisor), Orange County Supervisor Michelle Park Steel, former state Senate Minority Leader Bob Huff and former Orange County GOP chair Scott Baugh, who had been raising money to run in the neighboring 48th CD.

However, it would take a pretty elaborate top-two primary scenario, or a severely flawed Democratic nominee, for the GOP to hold this seat in this climate. The 39th CD moves from Lean Republican to Lean Democratic.