AMNA NAWAZ: Former President Donald Trump today made big promises to the American auto industry at the Detroit Economic Club, while team Harris embraced new campaign strategies.

Laura Barron-Lopez reports.

LAURA BARRON-LOPEZ: Former President Donald Trump spoke to the Detroit Economic Club for almost two hours today.

DONALD TRUMP, Former President of the United States (R) and Current U.S. Presidential Candidate: The four-year-long nightmare for the American autoworker ends the day I take the oath of office January 20.

It ends.

LAURA BARRON-LOPEZ: Without saying how he would pay for it, Trump pitched new tax incentives for American automakers and tax breaks for gas-powered car owners.

DONALD TRUMP: We will make interest on car loans fully deductible.

LAURA BARRON-LOPEZ: In an at-times rambling speech, Trump called his opponent, Kamala Harris, stupid, promised higher tariffs and claimed Detroit and the auto industry were failing.

DONALD TRUMP: It's a failing industry, just like it's a failing country right now.

We're a failing country.

We're a nation in decline.

I hope you know that.

Doesn't make me feel good to say it.

SHAWN FAIN, President, United Auto Workers: Today, it's the same story.

The job killer in chief is once again back in Michigan to do what he does best.

LAURA BARRON-LOPEZ: In a Harris campaign call ahead of Trump's speech, United Auto Workers president Shawn Fain slammed the former president's economic record.

SHAWN FAIN: He talks a big game.

He's always all -- he's all talk.

That's what he is.

But he's no action.

And his record was defined by plant closings, job loss and union LAURA BARRON-LOPEZ: busting.

Harris and her running mate, Tim Walz, are continuing their push to reach voters in new places.

MAN: You're probably surprised to see World of Warcraft on the vice president's Twitch channel, but we are looking to bring a new style of campaign rally to Twitch with the coach himself, Tim "W's in chat" (ph) Walz.

LAURA BARRON-LOPEZ: A Walz rally in Arizona last night streamed alongside the Twitch user known as Preheat while he played the popular online game World of Warcraft.

But Harris is still using familiar tactics and faces.

Former President Barack Obama will make his first appearance on the campaign trail tonight in Pittsburgh.

And former President Bill Clinton is hitting Southern states this weekend.

For the "PBS News Hour," I'm Laura Barron-Lopez.