If Donald Trump's base is having doubts about his presidency, they weren't evident in Minneapolis on Thursday night.

The city hosted Trump's first campaign rally since Democrats opened an impeachment inquiry into White House efforts to get Ukraine to investigate political rival Joe Biden as well as the origins of the Russia investigation.

"These people are sick, I tell you. Sick," Trump said of Democrats in front of what appeared to be a close-to-capacity crowd at the Target Center, which seats 19,300.

The president insisted he did nothing wrong on the call with Ukrainian President Volodymyr Zelensky, despite a partial transcript released by the White House that strongly suggested a quid pro quo. Trump also defended his contentious decision to pull U.S. troops out of Syria, which leaves Kurdish allies vulnerable to an ongoing attack from Turkey.

Most importantly, however, Trump told his supporters that attacks on his presidency are attacks on them, the people who put him in office.

"They want to erase your vote like it never existed. They want to erase your voice, they want to erase your future," he said.

Demonizing Democrats, and making it personal for his supporters, is old hat for Trump. It got him elected in 2016, helped get conservative judge Brett Kavanaugh confirmed to the Supreme Court and served as an effective counter during the Russia investigation.

Standing outside the arena, Rodney Fennern said, 'I pretty much have tingles going down my spine right now.' (Jason Burles/CBC)

The Ukraine allegations are in many ways the biggest threat to Trump's presidency, and he is telling supporters that any investigation of him is an indictment of their votes.

"Everybody is against him, including half of the Republicans, the establishment. He's fighting the establishment," said Rodney Fennern, waiting in line outside the Target Center.

To understand this moment in the United States, "it helps to know more about psychology than politics," said Peter Wehner, a senior fellow at the Ethics and Public Policy Center who worked for three Republican administrations.

Wehner believes conservative Trump supporters may be experiencing what he calls "cognitive accommodation" — they've adapted to so much unusual behavior that to turn on the president now would be too hard.

"At this point, condemnation of Trump is condemnation of themselves," said Wehner. "It's too painful. It's less about defending Trump than defending their own defense of Trump."

'A pretty amazing feeling'

Since the impeachment inquiry began, Trump has been undermining the basic facts of the investigation and insulting his political opponents.

It seems to be working with his supporters — at least those enthralled enough with Trump to wait in the rain to hear him speak in Minneapolis.

Standing outside the arena, Fennern was almost giddy. "I pretty much have tingles going down my spine right now," he said, wearing a T-shirt with the letters LGBT — which stood for Liberty, Guns, Beer and Trump.

Further down the line, 17-year-old Julia Narthaler bounced up and down wearing a bright-red Make American Great Again hoodie and a camo Trump hat — clothes she gets teased about for wearing at her high school, a three-hour drive away.

Seventeen-year-old Julia Narthaler said being at the Trump rally in Minneapolis was 'a pretty amazing feeling.' (Jason Burles/CBC)

She calls being at Trump's rally "a pretty amazing feeling."

This is key to understanding why Trump supporters remain loyal, according to those who study politics and psychology. Much of it boils down to how the president makes them feel — and when he's under pressure and lashes out, those feelings become even stronger.

Howard Lavine, director of the University of Minnesota's Center for the Study of Political Psychology, compares going to a Trump rally as akin to playing in an orchestra or dancing at a rave.

"The psychological benefits that accrue from loyalty are self-esteem and the eradication of uncertainty," Lavine said.

Media reinforcement

Wehner and Lavine say that loyalty is reinforced by conservative media — networks that repeat Trump's talking points and mimic his outrage. That was apparent among people at the Minneapolis rally.

Patty Boyer estimated she listens to as much as three hours of Rush Limbaugh's radio show every day and watches three hours of Fox News every night. That's when she makes her Republican-themed quilts, one of which was wrapped around her grand-nephew in the line outside the Target Center ahead of the rally.

Boyer calls Democrats "a bunch of losers" and said the impeachment inquiry has only made her support for Trump more fiercely. She also acknowledged that "he's got a tough row to hoe."

Trump supporter Patty Boyer listens to up to three hours of Rush Limbaugh on the radio every day and watches three hours of Fox News every night. (Jason Burles/CBC)

Despite this loyalty, there are signs the Ukrainian crisis and the fallout from the Syria decision could be different than previous fights for Trump.

Fox News published a poll this week showing that 51 per cent of respondents supported the impeachment and removal of the president — yes, Fox News. The president dismissed the findings on Twitter ("their pollster sucks!"), but if doubts about the president appear on Fox, will loyalists follow?

It's possible. John Wesa described himself as 100 per cent in Trump's camp, but admitted that sometimes, the president's rhetoric bothers him. Wesa can imagine a scenario where his loyalty to Trump could fade — if the president was guilty of war crimes, say, or said something Wesa believed was truly racist.

"But I haven't heard it. I haven't seen it."

Wehner said that what makes the Ukraine scandal potentially more damaging for Trump is not just what he's admitted to doing, but the sense there may be more revelations to come. But Wehner is not convinced it would significantly move the needle for Trump's base.

"Is there something conceivable to squander that support? Probably. I just don't know what it is."