Three Democrats and one Republican walk onto a stage. How well will they get along?

It is one of many key things to watch at tonight’s U.S. Senate debate in Los Angeles — the first time that top contenders Reps. Barbara Lee, Katie Porter, Adam Schiff, and former baseball star Steve Garvey face off in a televised debate.

Garvey, a first-time candidate, has run a low-key campaign since announcing his bid in October but ranks near the top of several recent polls. The event will be his first political debate — a chance to elevate his campaign message as a moderate Republican to a statewide audience.

But the debate could also be a risk for Garvey, who has little political experience and may not be able to handle other candidates’ pressure on his policy stances, said Christian Grose, professor of political science and public policy at the University of Southern California. It is difficult, however, to predict how Garvey will do, he said.

• Grose: “He’s a little bit of a black box.”

The three Democratic members of Congress — holding similar positions on many issues despite having nuanced track records — will continue to try distinguishing themselves from each other to appeal to undecided voters. The Democratic hopefuls have largely refrained from attacking each other at joint appearances so far. But with ballots going out on Feb. 5 for the March 5 primary and Garvey rising in the polls, that could change.

Porter and Lee, who are behind Garvey in recent polls, could promote themselves as true progressives and attack Schiff on his ties to the Democratic establishment and his relatively moderate voting record, Grose said.

But the three representatives may still be reluctant to target each other, said Democratic political consultant Andrew Acosta.

• Acosta: “If Schiff hits Porter, is he going to guarantee that those votes go to him? Or do they go to Barbara Lee?”

How to Watch the Debate

Schiff could also target Garvey’s inexperience and past votes for former President Donald Trump as a way to promote Garvey to Republican voters as the opponent, so Schiff can have an easy win in November without having to face another Democrat, some strategists and experts told CalMatters.

Or Schiff could also leave Garvey alone in hopes he does well in the debate and gains traction. No Republican has won statewide in California since 2006.

The debate is an opportunity for all four candidates to gain free media exposure. And if Garvey does well, he could consolidate the Republican vote, experts say. In the primary, the two leading vote-getters, no matter their party, advance to the Nov. 5 general election.