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

The Republican National Committee will release an ad during the debate Wednesday night promoting early voting -- a method that some in the GOP acknowledge they have fallen behind on in recent years.

Included in the ad are RNC Chairwoman Ronna McDaniel, former Vice President Pence and former President Trump, who promotes the party's new early voting effort launched earlier this year.

The party is also planning to have a Bank Your Vote booth in Milwaukee on Wednesday, with absentee ballot request forms from all 56 states and territories.

The GOP has struggled to regain parity with Democrats on early voting after Trump baselessly lambasted the method as ripe for widespread fraud, without providing evidence for his claims.

-ABC News' Tal Axelrod

President Joe Biden's reelection campaign was noncommittal Wednesday when asked if he would debate the ultimate GOP presidential nominee.

"We have not had a conversation about that at all," Biden campaign co-chair Cedric Richmond told reporters during a press conference Wednesday. "I'm sure one day we will. But it's not today and I don't have any news on that. But what we're going to continue to do is continue to govern because Vice President [Kamala] Harris and President Biden have a job to do and they take it serious. So when we have news on that, we’ll let you know."

Biden and his allies have gone after the entire Republican primary field, tying them all to the "MAGA" brand of former President Trump.

However, the future of presidential general election debates is up in the air after the Republican National Committee last year voted to quit the Commission on Presidential Debates, the non-partisan group that has put on general election debates since 1988.

Biden's campaign also defended its decision to not engage in any Democratic primary debates, boasting that the president, as the incumbent, is the presumed nominee despite facing challenges from Robert F. Kennedy Jr. and Marianne Williamson.

-ABC News' Tal Axelrod

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