Trump's rally is scheduled for 7:30 p.m. at the Fiserv Forum where the Republican National Convention was held in July. Supporters lining up to get in Friday afternoon are not only enthusiastic, they are optimistic that the former president will win on Tuesday.
VOTER GUIDE: Everything you need to know to vote in Illinois, Indiana and Wisconsin
As is often the case for Trump's rallies, many lined up hours early. Many in line are also from out of state, mostly from Illinois.
Republicans are fighting to win back Wisconsin this presidential cycle. It helped send Trump to the White House in 2016, but voted for Biden in 2020. That's why the RNC held their nominating convention in the city, and why Trump is making it his last campaign stop of the night.
Many of the people in line have been to Trump rallies before. John Kettman from LaSalle, Ill., said he already voted for Trump, and that the former president made him switch parties from Democrat to Republican.
ELECTION UPDATES: Harris calls Trump's Liz Cheney comments 'disqualifying'
Kathy Lurz of Barrington said she's voting for Trump, "For our Freedom, for our country. For the rights t just be who we are, illegal immigration. I believe in his values. Some things I don't believe in, but that I believe in."
"Hoping this is going to be the change we need and done fairly this time around," said Jessica Wells of Chicago.
But we found at least one person who hasn't yet made up their mind.
"Still undecided," said Aidan Rossie Weida, who is from Wisconsin and is voting for the first time. "I'm leaning toward Kamala, I would say, but I want to see Trump the man, not Trump the idea."
RELATED: Liz Cheney hits back at Trump's violent rhetoric: 'This is how dictators destroy free nations'
Polling shows the candidates essentially deadlocked in Wisconsin. Four of the past six presidential elections in Wisconsin have been decided by less than a point, or fewer than 23,000 votes.
Milwaukee is home to the most Democratic votes in Wisconsin, but its conservative suburbs are where most Republicans live and are a critical area for Trump as he tries to reclaim the state he narrowly won in 2016 and lost in 2020. One reason for his defeat was a drop in support in those Milwaukee suburbs and an increase in Democratic votes in the city.
Harris will hold a rally in West Allis, one of those crucial suburbs, at the state fairground at 8:30 p.m. Friday night.
Before heading to Milwaukee, Harris campaigned in the southern Wisconsin city of Janesville, where she talked up her support for organized labor in a speech at an International Brotherhood of Electrical Workers local.
"Nobody understands better than a union member that as Americans we all rise or fall together," Harris said. She promised to eliminate "unnecessary" degree requirements for federal jobs and push private sector employers to do the same.
She called Trump an "an existential threat to America's labor movement."
Harris said Trump is "one of the biggest losers of manufacturing jobs in American history," hanging on the word "loser' as she was flanked by union workers in bright yellow T-shirts.
The Associated Press contributed to this report.