Democrats' California nightmare

Democrats have one goal in 2018: win the House back. But California's 39th district is a case study in what can go wrong when the national party gets involved in local races.

The Democratic divide: The DCCC backs Gil Cisneros, one of six Democratic candidates. The California Teachers Association (the state's largest teachers union with 325,000 members who've spent millions on races in the past) announced its support for Mai Khanh Tran today. And the Bernie Sanders-aligned Our Revolution PAC backs Andy Thorburn.

Why this matters: Democrats could be locked out of the general election in CA-39 altogether — and one step further from winning the House — if Democratic energy and resources are divided among three candidates in a state with a top-two primary system.

• Yes, but: It is valid for the national party groups to try to get some candidates to drop out of crowded primaries to increase their challenges. They're just not unified.

The problem: The DCCC has already been criticized for elevating Cisneros over Tran — a California pediatrician endorsed by EMILY's List — for the perception that they "encourage all women to run and to speak up, and on the other side they prefer self-funded millionaires over any women [in the race]," Tran's campaign manager told ABC News.

• DCCC Chairman Rep. Ben Ray Lujan says the group's role is "to lean in in some of these races" in California. But intervening hasn't always worked, as we saw in TX-07 when they attacked Democratic candidate Laura Moser, who ultimately made it to the runoff.
• And now the group's preferred candidate in the race was accused of inappropriate behavior by a woman running for California's state assembly.

What they're doing: The DCCC is running a new TV ad campaign today through May 14 in CA-39, which is considered the most competitive in the state to replace retiring Rep. Ed Royce. The ads attack two second-tier Republican candidates, instead of other Democrats, likely as a way to split the Republican votes so no two GOP candidates earn higher votes than Democratic candidates.