DULUTH, Minn. — Hours before President Trump arrived in this city on Lake Superior, the host of a local conservative radio show marveled that Duluth was the lead of Fox News Radio’s national news roundup.

The last sitting president to visit was George W. Bush, in 2004, and the local newspaper’s editorial board deemed Trump’s arrival “a big deal, a rare deal, and an historic moment — even if it is mostly a political rally.” The radio host reflected on the changing politics of this once-Democratic stronghold and wondered what the president would say.

“You know, 60 million people voted for Trump. Trump won. He’s still winning, and he likes to say, ‘Don’t get sick of winning,’ ” said Brad Bennett, the host of “Sound OFF!” on Duluth’s WDSM-AM. “Hope he says that again tonight, because that will really get them fired up! ‘Don’t get sick of winning.’ ”

Hours later, Trump took the stage in a converted hockey arena and, within minutes, fulfilled the host’s wish.

“Remember, I used to say, in a little jest, but I really meant it: ‘We are going to win so much.’ Remember?” the president asked more than 8,000 supporters last Wednesday. “ ‘We are going to win, win, win.’ That’s what we are doing.”

Presidential visits are a big deal, no matter who is in the White House — but Trump’s arrival in a community can often feel as if he has cannonballed into a small pool, soaking anyone who is anywhere close by and leaving ripples that remain long after Air Force One has departed. Those affected are often giddy about being swept up in something so big or angered to have such a thing happen in their community.

In northeastern Minnesota last week, Trump’s goal was clear — to use his presence and the wall-to-wall media coverage to fire up local voters, in hopes that Republicans in November can flip a local U.S. House seat held by a Democrat. He also had a broader concern — to excite supporters across the country who could help Republicans hold on to House and Senate seats that Democrats are targeting. Trump has pitched a vote in the midterms for a Republican, any Republican, as a vote for him and his agenda.

On Wednesday, Trump is scheduled to hold a rally in Fargo, N.D., where Republicans hope they can oust Senate Democrat Heidi Heitkamp.

Since Trump’s election, Democrats have seen a burst of enthusiasm and activism, sweeping some special elections and state-level contests and giving Democrats hope they can ride a “blue wave” into the November elections.

Republicans are hopeful they can create a wave of their own — and if one is possible, it seems most easily created in the upper Midwest, where the president’s economic messages and cultural connection seem to resonate. Minnesota has not voted for a Republican for president since Richard M. Nixon in 1972, but Democrat Hillary Clinton won the state by only 1.5 percentage points — a point of pride for Trump, who hopes to win the state in 2020.

“We are on the national map in a very big way,” said Minnesota Republican Party Chair Jennifer Carnahan, who dove deep into the tidal metaphors as she addressed Trump’s rally crowd before his arrival. “Let’s show the world that there is no blue wave coming here in Minnesota. What we have building here is a red tsunami that’s bigger than a wave, and it’s rolling across Lake Superior right now.”

But it will be months before Minnesotans will know which, if any, wave will hit.

The president’s target last week was Minnesota’s 8th District, home to solidly conservative Minneapolis exurbs, liberal Duluth and the trending-conservative Iron Range, which has several major iron-ore mines that are expected to benefit from Trump’s imposition of tariffs on imported steel. The district represents one of just two highly competitive House seats held by Democrats, according to ratings by the Cook Political Report. The other is in southern Minnesota along the Iowa border.

At the same time, 22 Republican-held seats are considered toss-ups by Cook, including two in the Minneapolis suburbs. Democrats need a net gain of 23 seats to take control of the House.

If the benefit of a Trump visit is to fire up local Republicans, the downside is that he also is his opponents’ the biggest motivator. Hundreds of protesters gathered in downtown Duluth on Wednesday evening for a “Blue Wave Rally,” featuring four of the Democratic-Farmer-Labor Party candidates running for office in the 8th District, as well as other speakers. Some participants carried homemade signs that labeled the president a “racist,” “fascist” and a “liar” who should be impeached or locked up.

Ken Martin, the state Democratic Party chairman, warned the crowd that “if we don’t take power back from Donald Trump and the Republicans this year, I have news for you: We’re not going to beat Donald Trump in 2020.”

“Wave elections don’t just happen. If we want that wave to reach our shore, we have got to go out there!” Martin said in a passionate yell. “We go out there door to door, neighbor to neighbor, person to person, talking about our values. . . . We have to do a better job, all of us, of giving people a sense of what we stand for, who we are.”

For all the ardor at protests, Trump’s visits carry something harder to replicate — the grandeur of the presidency.

During the presidential campaign, Trump tried to hold as many rallies as he could in places like Duluth — struggling former industrial towns trying to create jobs for blue-collar workers who once would have easily found jobs in factories or mines.

These are the places that Washington has forgotten, Trump would say, filled with people who feel as if winning has passed them by. The campaign visits brought excitement, chaos and national attention; his visits as president even more so.

“We talk about the forgotten men and women,” Trump said last Wednesday in Duluth, prompting cheers. “They’re the smartest people. They work the hardest. They pay taxes. They do all of the things. And yet, they were the forgotten people.”

As with all of Trump’s rallies, the one in Duluth attracted people from all over. There were Minnesotans and other Midwesterners, including Wisconsinites who live just across the bridge. There were retirees who spend their summers here, vacationers and the “Front Row Joes,” Trump groupies who attend as many rallies as they can. Fox News carried the rally live.

“I felt the excitement right when I got out of the car. This was so much fun,” said Heidi Johnson, 57, a retired flight attendant who lives in Arizona — where she is excited to vote in contentious races there this fall — and whose family has a vacation home west of Duluth. This was her first Trump rally.

Trump concluded the business end of his rally early, calling to the microphone Pete Stauber, the Republican congressional candidate running in Minnesota’s 8th District. Stauber, the first House candidate to benefit from a Trump visit, seemed to bounce with excitement.

“Mr. President, these people support you,” said Stauber, standing before the largest audience he is likely ever to address. “Mr. President, these are the same people that are going to send me to Washington.”

Trump urged his supporters to vote for Stauber: “Pete is a great guy. You’ve got to get him a victory.”

Stauber made the most of his opportunity. He tweeted a photo of himself with the president in the back seat of the presidential limousine and thanked Trump “for supporting our way of life.”

In an interview with Fox News the morning after the rally — conducted at a local diner — Stauber gushed: “We were really excited, and the rally was just unbelievable.” That afternoon, his spokeswoman called the “national and even global” attention “truly amazing.”

The challenge for any president is to turn a rally into something more lasting — success on Election Day. Trump’s predecessor, Barack Obama, was never able to translate his popularity into decisive wins for his party in non-presidential-election years. Trump has struggled to carry party members over the finish line in special elections, but he has proved influential in primary contests. That leaves his impact in November unclear.

Trump may benefit most from his appearances; his rallies are usually hosted solely by Trump’s campaign, which retains tight control of information about those who sign up for tickets.

But campaign representatives say that anytime the president plugs a candidate — from sending a tweet to hosting a rally — they see a “Trump bump.” Often, that means more traffic on a campaign website, more likes on social media, more volunteers and more donations. After Trump hosted a rally in Nashville last month for Rep. Marsha Blackburn, who is running for a U.S. Senate seat in Tennessee, her campaign saw an increase in fundraising and volunteers. Campaign spokeswoman Abbi Sigler said people were talking about the rally for days.

“The benefits of his visit are felt in every part of our campaign,” she said, declining to share specific numbers.

As Trump supporters left the Duluth rally last week, few could name the congressional candidate Trump had called to the stage or any other election details. But many excitedly confirmed the notion of a red wave approaching the state. Jeannie Carling — who could name her congressional representative, Republican Tom Emmer — said that rallies are vital in a state such as Minnesota, where conservatives can feel outnumbered and drowned out. The Minneapolis suburbs, she said, have seen a backlash against Trump that she worries could hurt GOP candidates.

“There are a lot of us that are silent conservatives,” said Carling, 68, who lives in Oak Grove, north of Minneapolis, and attended the rally with her daughter. “You meet people who are feeling the same things, have the same perspective. People are pumped up.”

Nearby, dozens of young male Trump supporters tried to drown out young liberal protesters with chants of “Trump! Trump! Trump!” An elderly woman grabbed her husband’s shirt sleeve and pull him away from the action, smiling and shaking her head at him as she did so.

A young man stood on the roof of an adjacent parking garage and triumphantly waved an American flag decorated with Trump’s face, as the crowd below chanted “USA! USA! USA!”

The next day, the front page of the Duluth News Tribune proclaimed: “Trump playful in Duluth.” On his radio show, Bennett recapped the night’s events, reciting pieces of Trump’s speech and taking calls from listeners who were excited to see so many conservatives in one place.

He read aloud a Breitbart article that described northern Minnesota as “a land where hope has been reborn and support for the president runs extremely high.” As he discussed the rally with a caller, he paused.

“It was incredible, wasn’t it?” he asked.