Former President Donald Trump spent more than an hour ahead of Tuesday night's vice presidential debate campaigning in a Democratic county crucial to Kamala Harris' hopes for winning the key battleground state of Wisconsin.

Republican Trump appeared at a manufacturing facility in Waunakee, a suburb of Wisconsin's capital city of Madison in the Democratic stronghold of Dane County. Trump had never campaigned in Dane County nor visited as president.

In an event advertised as economic-themed, Trump bounced from subject to subject, also taking on Democratic nominee Harris on issues, including foreign policy, crime and immigration, while intermittently pivoting to criticism of outgoing President Joe Biden.

"I'm asking every citizen to join me in launching sort of a new golden age for America," Trump told hundreds inside Dane Manufacturing, a metal fabricator that has a long history of hosting Republican candidates and officeholders.

Trump also could not pass up a jab at former President Jimmy Carter on the Georgia Democrat's 100th birthday.

With hollow praise, Trump declared the one-term Carter "the happiest man" because he "is considered a brilliant president" compared with Biden. Trump did not note Carter's birthday, nor his status as the longest-living former president.

Later Tuesday, Trump was to hold an event at a museum in Milwaukee, Wisconsin's largest city and home to the state's largest number of Democratic voters and second-largest number of Republicans. His appearance there was also meant to give him reach into the city's conservative suburbs, a part of Wisconsin where his support has softened but where he must do well to win.

In Milwaukee, Trump was slated to speak in a small auditorium at Discovery World, a science museum along Lake Michigan's lakefront. His event was not open to the public and his audience was to consist only of news media.

Last Saturday, he held a rally in western Wisconsin where he blamed Harris for crimes committed by people in the country illegally.

Both of his planned stops were ahead of Tuesday's debate in New York between Trump's running mate JD Vance, a senator from Ohio, and Democratic vice presidential nominee Tim Walz, the governor of Minnesota.

Dane County, the location of Trump's first stop, is Wisconsin's fastest-growing county and an economic engine for the state, fueled by jobs in the health care and tech industries. It is also home to the University of Wisconsin.

Dane County's population grew by about 30,000 people between 2016 and 2020. It has gone up by an additional 13,000 since then, based on the most recent U.S. Census Bureau estimate.

That presents a challenge for Republicans, especially given that nearly 90% of registered voters in the county cast ballots in 2020. Biden won 75% of the vote that year in Dane County, beating Trump by 181,000 votes in the county while carrying the state by fewer than 21,000. Hillary Clinton beat Trump in Dane County in 2016 by 47 points, and Trump won the state by less than one point.

It's a point former Wisconsin Governor Tommy Thompson said he made to Trump. In remarks to the crowd before Trump arrived, Thompson said the former president should "go where the opposition is."

"And, the retort was, 'Isn't Madison very liberal?'" Thompson said. "Yes, but Dane County has the third-most Republican votes in the state of Wisconsin, and all we have to do is increase them."

Democratic presidential candidates have long come to Dane County to hold massive rallies to fire up the base. Harris campaigned there on September 20, holding a rally in Madison that attracted more than 10,000 people.

Waunakee, which bills itself as the "only Waunakee in the world," is slightly more Republican than the county as a whole. In 2020, Trump got 36% of the vote there compared to less than 23% countywide.