Watch as Barack Obama joined Tim Walz for a campaign event in Wisconsin on Tuesday, 22 October.
It came as in-person early voting kicked off across the battleground state.
The former president and Kamala Harris's VP pick hosted a rally in Madison, while Republicans hold events to encourage casting a ballot for Donald Trump before 5 November.
In the 2020 election, the former president lost the state by just under 21,000 votes.
Both Mr Trump and the vice president are expecting another razor-thin margin in the state and are pushing voters to cast their ballots early.
Though Mr Trump has been highly critical of voting by mail in the past, falsely claiming it was ripe with fraud, this time he and his team are embracing all forms of voting.
Mr Trump encouraged early voting at a rally in Wisconsin earlier in October.
