Win or lose, the United States Senate campaign that Kevin de León officially launches Wednesday in Los Angeles is a big deal.

For the record: California political professionals give de León, the state Senate president pro tem, little chance to win next year against fellow Democrat Dianne Feinstein, who is seeking a fifth full term in the U.S. Senate. They point to his disadvantages in fundraising and name recognition.

But on the way to the June 5 primary and (maybe) the Nov. 6 general election, de León’s candidacy can be significant, campaign-watchers say. It reflects major changes in California politics. And it can cause other changes to the status quo.

It will force Feinstein, for the first time in her quarter-century in the Senate, to mount a full primary campaign against a serious Democratic challenger. It will test the scope of the increasingly vocal left wing of the state’s dominant party, which has hammered Feinstein since she said in August that Donald Trump still has a chance to be a “good president.” It will provide an alternative for voters turned off by the incumbent’s age, 84, and Washington, D.C., insider status. It will force other potential candidates, such as billionaire liberal activist Tom Steyer, to decide sooner instead of later whether to enter the race. And, get this, it will allow California Republicans to dream of winning a statewide election for the first time since 2006.

I'm running for the U.S. Senate because you deserve a seat at the table. Please join my campaign: https://t.co/ddhhMNxTxd pic.twitter.com/O76i0DYNPq — Kevin de Leόn (@kdeleon) October 15, 2017

“On [the Democratic] side, this is a North-South battle. It’s a generational battle. It’s a philosophical battle. And it creates an opportunity for Republicans,” said California Republican Party Chairman Jim Brulte, who imagines a scenario in which de León and Feinstein savage each other in the primary campaign, raising public doubts about the survivor and setting up a GOP victory in the two-person election in November.

That’s the nightmare scenario for Democrats. The good news for them: No prominent Republican has yet entered the Senate race.

An uncomfortable if less frightening picture for state Democratic leaders is one in which the campaign carves up the party, bringing out the knives between its centrist and “progressive” wings.

De León’s candidacy, announced in messages to supporters on Sunday and to be kicked off with an event Wednesday at Los Angeles Trade Tech, is “certainly a mark of the shifting center of gravity in the Democratic Party in California,” said Parke Skelton, a Pasadena-based political consultant who isn’t involved in the U.S. Senate race.

“A case could be made that Dianne Feinstein is out of step with the zeitgeist,” Skelton said of the former San Francisco mayor. “On the other hand, [de León] can get all the best tables in Sacramento but outside Sacramento and his own Senate district is unknown.

“I think a big chunk of the California electorate is looking for the candidate who’s angriest at Donald Trump. But Feinstein can make the case that her being in the Senate and being on the Judiciary and Intelligence committees does more to protect us from the predations of Donald Trump than Kevin de León could.”

The data journalism website fivethirtyeight.com calculated that Feinstein has voted in the Senate “in support of President Trump’s agenda” 31 percent of the time, putting her more at odds than any other U.S. senator with her state’s anti-Trump electorate.

Bill Carrick, Feinstein’s L.A.-based political adviser, said de León is “trying to grab hold of this anti-Trump resistance.”

Although de Leon gained favor with anti-Trump Democrats by authoring California’s recent “sanctuary state” bill, Carrick noted that de Leon supported Hillary Clinton over progressive favorite Bernie Sanders in the 2016 Democratic presidential primaries. Carrick doubted de León can turn voters against Feinstein, who remained popular with 73 percent of Democrats in a September poll.

De Leon, 50, represents state Senate District 24, covering parts of downtown and East L.A. He faces term limits in 2018; running for the U.S. Senate will raise his profile and donor base for future races, with little downside. No other prominent Democrat has been willing to touch the race..

Win or lose, de Leon’s challenge to Feinstein is a game-changer.