One of Joe Biden's latest presidential campaign events in Minnesota was a Friday afternoon Zoom call with an invisible audience of unspecified size.

Holding forth was U.S. Sen. Amy Klobuchar, framed by bookshelves, talking up the former vice president in the latest of a series of "virtual roundtables" that have become a staple of the Biden campaign in Minnesota. It served as a prelude to the Democratic National Convention that gets underway on Monday, which will be almost entirely in cyberspace.

"What I love about Joe Biden is he gives people a plan, and passion, and a heart," Klobuchar said. "He gives you something to vote for, not just against."

While Biden and his surrogates chase votes via Zoom gatherings, text messages and phone calls, the re-election campaign of President Donald Trump in Minnesota has moved back to the kind of in-person campaign events that were a hallmark of pre-pandemic electioneering.

The opening of a new Trump field office in Anoka on Saturday was billed as part of a "seamless transition" to in-person campaigning.

Earlier this month, Republican U.S. Senate candidate Jason Lewis helped open a new "Trump Victory Office" in the St. Cloud area.

Both field offices are among the lengthy list of examples of the Trump campaign's deep dive into Minnesota, a state he has vowed to flip. The president himself is scheduled to be back in Minnesota on Monday for a campaign event in Mankato.

While the Biden campaign's real-time footprint remains light by traditional standards, the Trump campaign has swarmed the state with organizers, all with an aim of proving that Minnesota isn't as reliably Democratic on the presidential level as it's been all the way back to the 1976 election.

"We have built an infrastructure that's letting us engage communities on their own terms," said Preya Samsundar, spokeswoman for Trump's campaign in Minnesota.

So far this cycle the Trump campaign says it has made more than 2 million voter contacts in Minnesota — with more than a million of those just in the last month. The campaign defines "voter contacts" as direct conversation between a campaign worker or volunteers and prospective voters, either in person or on the phone.

The Biden campaign, working with the Minnesota DFL, reports some 800,000 voter contacts. In contrast to the Trump campaign, the Biden campaign counts texts and other kinds of online contact. But they have eschewed door-knocking and in-person events.

"I think we're in a very good place and that the tactics we're using right now are working," said Corey Day, senior adviser to the Biden campaign for Minnesota and a former executive director of the Minnesota DFL.

The differing approaches echo the split between the two major political parties on how to respond to the pandemic, with Republicans generally much more dismissive of shutdown orders, mask mandates and limits on group gatherings. Samsundar said campaign outreach workers are following public health guidelines, wearing masks and socially distancing as they knock doors.

In recent weeks, masked volunteers for the Trump campaign have fanned across the state to knock on doors in pursuit of votes. Trump Victory Offices have been holding meetups at a steady clip in recent weeks, with the "Minnesota Trump Victory" Twitter account posting a constant stream of photos of volunteers, activists and candidates gathering for picnics and watch parties and canvasses.

Trump goes rural

Most of the organized activity takes place outside the Twin Cities, reflecting Trump's rural base of support in a state he narrowly lost in 2016. Photos show plenty of indoor gatherings, often with lots of unmasked participants. Altogether, it gives the Trump campaign a degree of visibility around the state that Biden has yet to attain.

"The thing that's keeping me up at night right now is asking whether I made the right decision about campaigning virtually," said DFL Chairman Ken Martin. "At times I feel like we have one hand tied behind our back in a fight with a guy who's fully armed in a way we haven't seen before."

Trump's big bet on Minnesota — which includes moving advertising dollars from other battleground states — has become fodder for fundraising pitches by DFL candidates trying to cultivate a sense of urgency.

"The GOP's massive investment in Minnesota is already moving the needle for them," Sen. Tina Smith wrote in a recent pitch to donors. "This should be a wake-up call."

Lewis, meanwhile, has tried to tie his opponent to Biden's largely homebound campaign. "My opponent, Tina Smith, she's stuck in the basement with Joe Biden right now," he said at the Waite Park GOP event. A vocal critic of Gov. Tim Walz's coronavirus restrictions, Lewis has been active in his public appearances since nearly the start of the pandemic. Smith's campaign noted she has made multiple public appearances in the past week, including multiple Twin Cities stops as well as in Hibbing, Cass Lake and Bemidji.

The Biden campaign's Minnesota efforts, at least so far, have been considerably less numerous. That's partly a function of political circumstances: while Trump entered 2020 as the presumptive Republican nominee, Biden didn't clinch his party's nomination until early June.

Still, Biden will benefit from the organizing and fund­raising strength of the DFL, which in recent years has far outpaced Minnesota Republicans in dollars raised and statewide election victories. This year, the DFL has raised more than twice that of the Minnesota Republican Party, and had more than double the amount of money in the bank at the end of the last fundraising period.

"What's true is that people are picking up the phone when we call, they are responding to the texts, the quality of the conversations we're having and the level of engagement we're seeing is much deeper than in previous cycles," Martin said. "We have the momentum in this state, and I've seen a lot of indicators that suggest President Trump is not on track to do as well here as he did in '16."

Biden ups game in Minn.

In the past few weeks, the Biden campaign has been shifting its own people into Minnesota — bringing on a state director, a senior adviser, a political director and a communications director. None of that was in place when he won the state's Democratic primary in March.

"We're raising the resources. We're building major capacity here," Day said. "Obviously this is a much different kind of election than anything we've ever seen, and I think we're doing this in a way that's thoughtful, somewhat out of the box and creative. I am proud we're putting safety first, making sure our folks and our volunteers are safe."

Earlier virtual roundtables featured national party leaders such as California U.S. Sen. Kamala Harris, now Biden's running mate. Gov. Tim Walz and Lt. Gov. Peggy Flanagan held another "virtual conversation" on Wednesday.

During Saturday's event with Klobuchar, the tactic also showed its limits. As the roundtable was wrapping up, a participant tried to take questions from listeners. A disembodied voice piped up: "We aren't able to do questions now because of technical difficulties."

Patrick Condon • 612-673-4413