A group of more than 100 anti-Republican protestors temporarily took to the street outside Fiserv Forum after the debate began.

The group was advocating on behalf of several causes championed by the left, carrying signs advocating for abortion rights, transgender rights, immigrant rights and Black Lives Matter, among other causes.

Some of the signs were more explicitly political in nature, directly targeting GOP candidates.

One protestor carried a sign reading “Down with DeSantis.”

The group cheered, whistled and chanted as they advanced down the street.

“Get up, get down, Milwaukee is a union town,” was one chant that could be heard.

The protestors were accompanied by legal observers.

The group walked down an open street and at one point briefly blocked traffic. The protestors were otherwise peaceful and dissipated soon after they began.

-ABC News’ Allison Pecorin and Olivia Osteen

The candidates came to the debate prepared with answers about abortion – carefully considering their wording, and, in a stark departure from the first half hour, actually answering the moderators’ question on the issue.

One thing the candidates didn’t want to talk about? Climate change. The moderators asked the candidates to raise their hand if they believed human behavior was driving climate change — but that didn’t happen. Instead, DeSantis said he wanted to debate rather than answer a question like “school children.” Ramaswamy chimed in to say “the climate change agenda is a hoax,” drawing boos from the crowd, though it wasn’t clear what exactly they were booing. Christie jumped in to say that Ramaswamy sounded like both ChatGPT and Obama. Haley decided that this was the moment to quote Margaret Thatcher — “if you want something done ask a woman” — though she did answer that climate change was real, putting the onus on China. And Scott used the moment to chide the rest of the field for being “childish.”

— Analysis by Leah Askarinam of FiveThirtyEight

Christie again focused on his record as New Jersey governor when asked about how he'd address shootings and gun violence plaguing the nation.

He accused prosecutors of not arresting violent criminals and said a "President Christie" would appoint attorney general to instruct U.S. attorney to do so.

"We have plenty of room in the federal prisons to lock up these violent criminals and clean up what's going on all across this country and these individuals," Christie said.

During the abortion back-and-forth, Pence claimed that 70 percent of Americans support a 15-week abortion ban. He’s cherry picking the results from one poll.

A 2022 survey from the Center for American Political Studies at Harvard University and The Harris Poll asked respondents, "Do you think your state should allow abortion…?”

Twenty-three percent said up to 15 weeks, 12 percent said up to six weeks and 37 percent said only in cases of rape and incest. That’s 72 percent all together. But answers in surveys vary greatly depending on how the question is asked.

A 2022 Economist/YouGov poll asked specifically about a 15-week ban — 39 percent supported it, 46 percent opposed it. A 2023 PBS NewsHour/NPR/Marist poll asked respondents whether abortion should be allowed up until 24 weeks — 44 percent said yes.

-Aaron Sharockman, PolitiFact

The 2024 presidential election has been underway for months, but with tonight’s first Republican primary debate in Milwaukee, we’re kicking off a new phase of the campaign. In these final five months before voting begins, we’re going to have monthly debates, dashes through Iowa, big-money fundraisers — and probably a culling of the field.

Tonight’s debate will feature eight candidates. Front-runner Donald Trump, who has a 37-percentage-point lead in FiveThirtyEight’s national polling average, will not be among them, as he has opted to skip the debate. Instead, we will hear from Florida Gov. Ron DeSantis; entrepreneur Vivek Ramaswamy; former Vice President Mike Pence; Sen. Tim Scott; former U.N. Ambassador Nikki Haley; former Arkansas Gov. Asa Hutchinson; North Dakota Gov. Doug Burgum; and former New Jersey Gov. Chris Christie.

There are a few threads and tensions we’re going to be watching tonight. First, in the absence of Trump, will his challengers’ attempts to position themselves as a more favorable option fall flat? How will candidates make their case for being a better alternative to Trump without having the contrast on stage beside them? Secondly, what sort of friction will we see between the anti-Trump candidates and those running on more similar ideas or rhetoric?

We’ll keep an eye on all this and more. You’ll be hearing from the crew at FiveThirtyEight and ABC News — as well as some new friends at PolitiFact — throughout the night. The Fox News-hosted debate begins at 9 p.m. Eastern, and we have some colleagues on the ground in Milwaukee who will ensure you’re going in with everything you need to know.

Thanks for joining us. Stay tuned as we update the blog with real-time analysis, charts, thoughts, questions, ideas, idle fancies and more. Leading up until the debate starts, we’ll run through the state of the race so far. Once the debate starts, we’ll make sure we’re addressing everything happening on stage, including what issues the candidates talk about, who they attack, how they position themselves and what Americans think.

-Analysis by Maya Sweedler of FiveThirtyEight