Why House Dems are "closely" watching the California primaries

• California Democratic Reps. Mike Thompson, Doris Matsui and Brad Sherman — all 70 or older — are among those facing tough primary fights with younger Democratic challengers.
• Their Democratic colleagues are watching "all of them closely," one senior House Democrat said, as well as the LA mayor's race and the state's gubernatorial election.
• "Just to see the anti-incumbent sentiment," another senior House Democrat told Axios.

State of play: June 2 is California's jungle primary, in which all candidates for a given office run in one contest and the top two vote-getters — regardless of party — advance to a runoff in November.

• Often, that dynamic matches up the top-performing Democrat and Republican. However, in several deeply blue House districts, the incumbent is more likely to face another Democrat in the fall.
• This year, an unusually large number of incumbents are facing well-funded challengers who are going after their lengthy tenures and arguing that it is time for a new generation of Democratic leaders.

These are the House races that Democrats have their eyes on:

California's 4th District: Thompson, a 75-year-old member of the centrist Blue Dog Coalition first elected in 1998, is trying to fend off 35-year-old venture capitalist Eric Jones.

• Both Democrats have raised huge sums, with Thompson bringing in just under $3 million as of March 31 and Jones raising over $3.2 million over the same period, including a $364,000 personal loan.
• Jones has tried to harness anti-incumbency sentiment, with ads declaring that "too many Democrats have been in Washington so long, they're not up to the fight," and hitting Thompson as "corrupt" and "ineffective."
• Thompson, for his part, has played up his anti-Trump bona fides and hit Jones on his corporate background by depicting him as a "lapdog for big corporations."

California's 7th District: 81-year-old Rep. Doris Matsui, who took office in 2005, is facing a stiff challenge from progressive former Sacramento City Council member Mai Vang, 41, who has been endorsed by the Sacramento Bee.

• Matsui has raised eyebrows with a red box on her website (a method campaigns use to signal super PACs) touting GOP candidate Zachariah Wooden, in what progressives say is a tactic to box Vang out of the runoff.
• Inclusion PAC — an outside group whose only listed donor, a local union, also donated to Matsui's campaign — has filed with the FEC to spend over $100,000 on ads promoting Wooden.

• This is another race defined by negative campaigning, with Vang's red box advocating "purely negative messaging against the incumbent."

California's 32nd District: Rep. Brad Sherman, a 71-year-old who has been in office since 1997, is being challenged by Jake Levine, a 42-year-old former Biden administration official.

• Levine's campaign has, perhaps more than any other primary insurgent's, made Sherman's length of service a central issue in its messaging, running multiple ads targeting the incumbent's 30-year tenure.
• Sherman's campaign has largely ignored Levine — his red box encourages PACs not to mention him — and has focused on portraying him as a hard-charging, anti-Trump crusader who delivers for his district.

Zoom out: Several incumbents below retirement age are also facing credible progressive primary challengers, including Reps. Ami Bera in the state's 3rd District and Jimmy Gomez in the 34th District.

• There are a slew of hotly contested open primaries as well, including to replace former House Speaker Nancy Pelosi (D-Calif.) in the 11th District.
• In the 22nd District, State Assembly member Jasmeet Bains has the backing of House Democrats' campaign arm to take on GOP Rep. David Valadao, but first she has to defeat progressive Randy Villegas.