Former Pennsylvania senator Rick Santorum will be one of just four candidates participating in a Republican undercard debate Wednesday in Simi Valley, Calif. (Christian Gooden/St. Louis Post-Dispatch via AP)

So how in the world do you win a debate for losers?

“Don’t go,” said Allan Louden, a debate coach, a professor at Wake Forest University and an occasional adviser to political candidates. “I’m serious.”

On Wednesday evening, four long-shot Republican candidates will step onstage and into one of the weirdest — and most difficult — moments in the history of presidential debates.

There will be no way for them to confront the front-runner face to face, the usual tactic of an underdog. Donald Trump won’t even appear until after they’re finished, to face 10 other candidates in the night’s main event.

For these four long shots, there will also be little point in confronting one another.

The strongest of them, former senator Rick Santorum (Pa.), has been polling at 0.8 percent, according to CNN’s most recent average of major polls. If one of the others somehow swiped all of his support, that candidate would be at less than 1.5 percent.

Finally, unlike a similar event last month in Cleveland, this debate won’t even offer a chance to make a first impression.

In that debate, businesswoman Carly Fiorina introduced herself with a sharp and steady performance, and she got moved up to the main event this time. But for the rest, this is a repeat. TV debate No. 2. Or, in Santorum’s case, No. 22.

But still, they’re going. Deprived of other options, all four are hoping to use this moment as a springboard.

They believe — you have to believe — that being involved in a sad spectacle on national television is better than not being on national television at all.

“In an odd way, it might actually be better for Senator Santorum to be center stage in the early debate than to be a Chris Christie or a John Kasich . . . on the wings of the second debate,” said Matt Beynon, a spokesman for Santorum, putting the best face on things. “Where Senator Santorum might have 20 to 25 minutes to talk, those folks — from [Santorum’s] experience four years ago, they’re really only going to have four or five minutes to talk.”

Beyond Santorum, the other three candidates on the undercard are Louisiana Gov. Bobby Jindal, Sen. Lindsey O. Graham (S.C.) and former New York governor George E. Pataki. They will debate at 6 p.m. Eastern time on CNN, standing on the same stage that the main-event debate will use, at the Ronald Reagan Presidential Library in Simi Valley, Calif. The bigger debate starts at 8 p.m.

In the 2016 race for the White House, some frontrunners are gaining ground, while others are slipping. From Donald Trump to Hillary Clinton, who is staying strong in the polls? We break down the big takeaways from the latest Washington Post-ABC News poll. (Julie Percha/The Washington Post)

There will be two notable changes from the first undercard that will make the early debate more like the late one. Both debates will share a moderator: CNN anchor Jake Tapper. And they will share a crowd. After the cavernous arena was largely empty for the lower-tier candidates in the first debate, CNN will require spectators to be in their seats for both debates Wednesday.

Even so, this time might be more depressing for the long shots: There are fewer of them now.

Fiorina got promoted, which means they didn’t. Former Texas governor Rick Perry, who was supposed to get the center spot onstage, exited the race.

And former Virginia governor James S. Gilmore III wasn’t even invited, because he couldn’t meet a requirement to reach 1 percent in three major polls. Which means there might be a fate worse than dropping out.

The result is an entire televised major-party debate in which none of the participants are solidly above 1 percent.

“Who are they debating? Are they debating each other? Are they debating the [leading GOP] candidates in absentia? Are they debating the Democrats?” said Alan Schroeder, a professor at Northeastern University who has written several books about presidential debates. “The normal dynamic of comparing and contrasting yourself with your competitors is out the window. There’s no clear purpose to this debate.”

Still, Fiorina made it out, giving the remaining four some hope.

“Like the last debate, this next debate is likely to reshuffle the deck,” Kyle Plotkin, a spokesman for Jindal, said in an e-mail. “Expect at least one breakout appearance from the undercard debate.”

Plotkin did not respond to questions about Jindal’s actual debate strategy. Lately, Jindal has bet his candidacy on an all-out attack on Trump — portraying the front-runner as an unserious huckster without real conservative principles.

“I don’t think he’s read the Bible, because he’s not in it. This is a complete narcissist. It’s been a fun show,” Jindal told CNN’s Wolf Blitzer. “The idea of Donald Trump is great. The reality is awful.”

Pataki, too, has spent much of his campaign tearing down Trump — although with less snark. In the debate, he may repeat an often-used argument: After summer flirtations with non-politicians such as Trump and neurosurgeon Ben Carson, voters will choose political experience in the end.

“Come this fall, people are going to want government,” Pataki said recently.

Graham is polling the lowest of the four long shots — since the August debate, CNN has him at 0.28 percent. His campaign also declined to talk about debate strategy. But he is likely to talk about his opposition to the nuclear deal with Iran, which is at the center of an unusually grim campaign that promises war and sacrifice if Graham is elected.

To succeed in this debate, Graham will have to project more energy than he did in the first debate, in which his demeanor was almost morose.

“If Lindsey Graham is like he was at the last undercard debate, I don’t think he’s going to make it to South Carolina” for his home-state primary, said Geoffrey Skelley, an analyst at the University of Virginia Center for Politics. “It was like somebody had killed his dog.”

Santorum is likely to talk about his plans to reduce both legal and illegal immigration. If he can stand out, his campaign is ready to take advantage as Fiorina’s did last time.

“They did a really good job of preparing — not just onstage, but as a campaign — to take advantage of things,” said Beynon, Santorum’s spokesman. “In my inbox, I had a fundraising e-mail from Carly Fiorina literally 30 seconds after that debate ended, and I’m not even on her list.”

Many argue that the lower-tier candidates should focus on things that unite Republicans, like attacking Democrats or, in Reagan’s own library, showing some Reagan-esque optimism for the future.

“Some kind of statement that has some kind of uplift to it, that would make them different. That’s the only thing I can think of, quite honestly. Otherwise I can’t think of anything,” said Kenneth Khachigian, a longtime Republican debate adviser.

Wait. He thought of one more thing.

“For Heaven’s sakes,” Khachigian said, don’t actually compare yourself with Ronald Reagan. On this night, he said, “it’s going to be the biggest cliche in the world.”