LONDON — Boris Johnson was jeered during his first trip as prime minister to Scotland on Monday.

He didn’t get the warmest reception from the first minister of Scotland, Nicola Sturgeon, either.

“The people of Scotland did not vote for this Tory government, they didn't vote for this new prime minister, they didn't vote for Brexit and they certainly didn’t vote for a catastrophic no-deal Brexit, which Boris Johnson is now planning for,” she said ahead of their meeting.

Johnson left Sturgeon’s official residence out the back door, avoiding another confrontation with protesters.

It has become something of a ritual for British leaders to demonstrate their commitment to the union with an early tour of England, Scotland, Wales and Northern Ireland — or, as Johnson called them, “the awesome foursome that are incarnated in that red, white and blue flag.”

Former London mayor and now new British prime minister, Boris Johnson is seen as a nontraditional politician. Here’s why. (Allie Caren/The Washington Post)

But there is much animosity toward Johnson in Scotland and palpable dread over leaving the European Union — especially by way of the hard, “no-deal Brexit” that the new prime minister says Britain must prepare for.

All of which has led to renewed talk of a crackup.

On Johnson’s first full day as Britain’s head of government last week, Ian Blackford, the Scottish National Party’s loquacious leader in Parliament, stood in the House of Commons and welcomed “the last prime minister of the United Kingdom.”

Scottish voters rejected independence, 55 percent to 45 percent, in a referendum in 2014. Now, Scottish nationalists are hoping that Johnson’s premiership will help their cause. Blackford has called Johnson a “recruiting tool.”

Sunday Times poll last month, before Johnson’s selection, found that 49 percent of Scots favored independence but that the number would rise to 53 percent in the event Johnson became prime minister.

It is far from clear whether Johnson will continue to tip the scales in favor of independence or whether the new prime minister may yet win over Scots with his shiny optimism and numerous public-spending pledges.

In Scotland on Monday, Johnson praised “the most successful political and economic union in history” and sought to assure the north that “we are a global brand, and together we are safer, stronger and more prosperous.”

He also voiced his opposition to another independence vote, calling the 2014 referendum a “once-in-a-generation event” and warning that a do-over would undermine public faith in democracy.

Johnson defended his assertion that former prime minister Theresa May’s withdrawal agreement was “dead” and that he could strike a new, better deal — despite assertions by European leaders that there will be no renegotiation.

“We are not aiming for a no-deal Brexit at all,” Johnson told reporters, even as his new minister charged with preparing for a no-deal departure, Michael Gove, said the government now assumed it would exit without a deal.

John Curtice, a politics professor at the University of Strathclyde in Glasgow, said that if a Johnson government leaves the bloc without a deal, “and if it’s as bad as some claim it will be, then obviously it’s easier for the [Scottish Nationalist Party] to pursue the independence argument.”

Curtice added that Johnson — who was a leader of the Brexit campaign in 2016 — is deeply unpopular across the United Kingdom with people who voted against Brexit. Scotland and Northern Ireland voted to remain in the E.U.; England and Wales voted to leave.

Scottish nationalists are not alone in warning of the union coming apart.

In a rare intervention in British politics, Irish Prime Minister Leo Varadkar said Friday, “One of the things, ironically, that could really undermine the union, the United Kingdom union, is a hard Brexit.”

Varadkar suggested that “a nationalist Britain” might encourage more people in Northern Ireland to want to dissociate themselves.

“People who you might describe as moderate nationalists or moderate Catholics, who were more or less happy with the status quo, will look more towards a united Ireland,” Varadkar said.

Some in Britain have sounded similar alarm bells. May’s de facto deputy prime minister, David Lidington, told the BBC this month that the union “would be under much greater strain in the event of a no-deal.”

He added, “My view comes not just from Scottish nationalism and pressure for Irish unification — it comes from indifference among English opinion to the value of the union.”

Gordon Brown, a former Labour Party prime minister, said at an event in London last week that Johnson could be remembered “not as the 55th prime minister of the U.K. but as the first prime minister of England.”

To win his new role, Johnson prevailed with a total 92,153 votes in a contest that involved only dues-paying members of the Conservative Party — who make up about 0.35 percent of the U.K. electorate and largely live in the southern half of England.

Hours after he won, hundreds of protesters gathered in central Glasgow, some carrying placards that read: “Boris No! Independence Yes!”

“It’s an English vote, an English prime minister,” said Gary Kelly, 44, who started planning the protest a week before. “Boris is a racist, a homophobe. He’s a bigot. He’s not the kind of person Scotland wants representing them.”

A YouGov survey last week showed that 65 percent of Scots thought that Johnson would be a “poor” or “terrible” prime minister.

Even Ruth Davidson, who should be Johnson’s natural ally as leader of the Conservative Party in Scotland, has been notably lukewarm on him.

Davidson — who has helped her party transform its fortunes north of the border, winning 13 seats in Parliament in the last election — reportedly banned Johnson from attending the recent Scottish Tory conference. She backed his rivals in the leadership contest. During the 2016 E.U. referendum, she fired up the pro-E.U. side by saying that Johnson’s side had told lies.

Now that Johnson is leader, Davidson has said she will judge him “by his actions in office.” They met together Monday.

“He’s a disaster for her,” said Thomas Lundberg, a lecturer in politics at the University of Glasgow. Johnson represents the “quintessentially English posh person who has made it through privilege and contacts rather than merit,” he said.

Johnson has dismissed accusations that he is unpopular in Scotland. When asked about it in Parliament last week, he responded by explaining “why I seem to get a good reception in Scotland.”

“It may be because the people of Scotland recognize that they have a common-sensical Conservative approach, which would not hand back control of their fisheries to Brussels just as Scotland has regained control of its fantastic fish,” he said.