Scotland’s first minister told British Prime Minister Boris Johnson that a second referendum on Scottish independence was inevitable as Johnson called a crisis summit of the United Kingdom’s devolved nations.

First Minister Nicola Sturgeon spoke with Johnson on Sunday for the first time since her pro-independence Scottish National Party won a plurality in Scottish parliamentary elections last week, the SNP said in a statement. Sturgeon reiterated her commitment to another vote on independence from the United Kingdom “when the [covid-19] crisis is over, and made clear that the question of a referendum is now a matter of when — not if,” a party representative said.

The SNP won 64 seats in the elections, one short of a majority in Scotland’s 129-member assembly. Combined with eight members of the Scottish Greens, the pro-independence camp will dominate the new parliament.

Sturgeon has said the final tally indicated that a new referendum was the “will of the country” and suggested in a BBC appearance Sunday that she could introduce a referendum bill as early as next spring if the United Kingdom has recovered sufficiently from the coronavirus pandemic and its economic effects by then. The SNP has said it wants a referendum by 2023.

Such a vote could sunder Scotland’s 314-year-old union with England. Johnson has rejected calls for a second independence vote, telling the Daily Telegraph that in “the current context” it would be “irresponsible and reckless.”

But the election results appear to have caused concern on Downing Street. Johnson wrote to Sturgeon on Saturday to congratulate her on her electoral success and invite her to a summit with leaders of Wales and Northern Ireland to “discuss our shared challenges and how we can work together in the coming months and years to overcome them.”

In the letter, Johnson made a case for preserving the union, highlighting the vaccination campaign as an example of “Team UK in action.”

“I believe passionately that the interests of people across the UK and in particular the people of Scotland are best served when we work together,” Johnson wrote. “We have shown that through the vaccine rollout. The UK Government’s ability to procure vaccines at scale has benefited people in all parts of our country.”

Johnson and his government argue that recovering from the pandemic should take priority across the United Kingdom. Overcoming the societal aftereffects of covid-19, Johnson wrote, “will require us to show the same spirit of unity and cooperation that marked our fight against the pandemic.”

Fifty-five percent of Scots voted in 2014 to remain in the union, but public opinion since then has shifted. Sixty-two percent of Scots voted in 2016 against Brexit; supporters of independence speak of an autonomous Scotland returning to the European Union.

Polls late last year showed support for independence peaking at 58 percent. But it fell after a sexual harassment scandal involving Sturgeon’s predecessor, Alex Salmond, and the success of the British vaccination drive. The country is now about evenly split on the issue, and many Scots tell pollsters that they want their regional government to prioritize economic recovery after steep pandemic losses.

Sturgeon said over the weekend that she would focus immediate attention on that recovery. She also said she would work with Johnson to ensure upcoming U.N. climate talks in Glasgow go smoothly, according to the SNP.

Still, she told British media that “when the time is right” the people of Scotland should have the right to decide whether they wish to separate from the United Kingdom.

The British government says Scotland would need permission from the British Parliament to hold a second referendum. Johnson’s government appears unlikely to grant that approval, at least any time soon. Absent a green light from London, analysts expect the Scottish government to argue its authority to call a vote in court.

Cabinet Office Minister Michael Gove told the BBC on Sunday that the British government was not interested in entertaining hypotheticals about a court challenge. But he also said the election results showed that Scots are not “agitating” for a vote.

Sturgeon told Sky News Sunday that she hoped to avoid a court battle.

“If we end up in court — which is not something I want to see — that would only be because we had a U.K. government that refused to accept Scottish democracy.”

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