Republican debate highlights and analysis: Fiery faceoff on Trump, Ukraine and more

President Joe Biden said earlier Wednesday that he will try to watch some of the debate that could help determine who his opponent will be next year.

Yet when asked by a reporter what his "expectation" is, Biden simply responded, "I have none," with a laugh.

Trump, the primary front-runner so far, is not appearing at Wednesday's debate, lowering the chances that Biden's general election opponent will be on stage.

-ABC News' Tal Axelrod

In the aftermath of a debate, it can be hard to figure out the actual impact of a viral moment or heated exchange. Here are some data-driven approaches that can help cut through the noise:

First, ignore “instant polls” that ask questions only among people who watched the debate. That group is not likely to represent the feelings of the broader population. Instead, look for post-debate polls — (like ours with Ipsos and the Washington Post) — that ask questions among the same group of Americans both pre- and post-debate.

Second, in the days following the debate, look at data that captures attention to candidates, such as trends in search results or media coverage, to determine which candidate made the biggest splash. Media attention is crucial for candidates who aren’t well known to gain traction in the polls and with donors.

Finally, look for changes in horse-race polls in the week or two after the debate. There is a lot of noise in primary polls (especially this time around) and it can take some time for changes in public opinion to be reflected in our polling average.

The big thing to remember is that what’s important to journalists and television pundits may not be what’s important to the public, and we have to wait for pollsters to ask them how they feel.

-Analysis by G. Elliott Morris of FiveThirtyEight

They didn’t qualify for the debate stage. Now, they’re vowing to take legal action.

Holding his own press conference outside the debate venue earlier Wednesday, Elder said he would file a formal complaint with the Federal Election Commission if wasn’t allowed on stage -- which he later followed through on.

ABC asked him if he still plans on watching or attending the debate if they don't respond, to which he said: "I'll be there, one way or the other, but I'm going to be up on that stage, trust me. If I were a betting person, and I'm not, I would bet the forum that Larry Elder is going to be on that debate stage.”

Johnson is planning to file two lawsuits against the GOP, he said in an interview with ABC News Radio National Correspondent Steven Portnoy.

Ahead of the debate, Johnson’s team was spotted across the street from the Fiserv Forum wearing "Perry vs Everybody" shirts.

On Tuesday, McDaniel told ABC News Senior Congressional Correspondent Rachel Scott that the party was not trying to spite candidates who did not reach their requirements.

“They’ve got time for other debates and they can still continue to work towards California in September,” McDaniel said. “This has nothing to do with them. We just stuck to our rules.”

-ABC News' Kendall Ross, Gabriella Abdul-Hakim and Isabella Murray

Burgum’s debate appearance was in doubt after he suffered an injury while playing pick-up basketball with his staff.

Just hours before the start time, he announced he’ll be on stage after all.

His team is already fundraising off the incident, selling T-shirts with a silhouette of a cowboy hat-clad Burgum playing basketball -- a twist on the famous Nike Air Jordan "Jumpman" logo.

Earlier in the day, the governor was visibly emotional as he discussed the pain he was feeling with ABC News.

"I'm someone who's never taken prescription pain meds and I'm not doing that today. Even though people said that'd be a good idea. Because I’d rather … I mean so many Americans make so many sacrifices, think law enforcement, think of military, what they do for all of us," he said.

"I mean, if you're gonna lead this country, you got to be able to stand on one leg for two hours. You know, it's not, it's not 'Dancing with the Stars.'"

-ABC News' Alexandra Hutzler and Oren Oppenheim