Richard Leonard, the Scottish Labour leader, is to ask his party to back an automatic second referendum on Brexit and to support remain, to head off a crisis over the party’s disastrous European election.

Scottish Labour officials said the new policy would be put to the party’s executive committee a week on Saturday after it suffered its worst election result since 1910, winning only 9.3% of the European parliament vote.

It would commit the party to backing remain in a second referendum, even if Jeremy Corbyn succeeded in reshaping the Brexit deal to meet Labour’s tests, Leonard’s spokeswoman said.

About 62% of Scottish voters backed remain parties last week, including nearly 38% who voted for the Scottish National party.

The dramatic switch in policy emerged after Leonard chaired a second crisis meeting on Tuesday evening, called by his MSPs at Holyrood after two frontbenchers quit their roles earlier on Tuesday.

In the first blow for Leonard, his close ally and friend Neil Findlay quit as Scottish Labour’s election coordinator and Brexit spokesman just before noon, blaming party infighting for his decision to resign.

His resignation came moments before Leonard held his first tense meeting with MSPs at Holyrood at lunchtime, where Leonard confirmed he now backed calls for a fresh EU referendum on whichever Brexit deal came forward.

But that significant concession failed to satisfy Daniel Johnson, the centrist Labour MSP for Edinburgh Southern, who quit his post as Scottish Labour’s justice spokesman in protest at Leonard’s failure to offer cast-iron assurances about whether his switch to backing a second EU referendum would urgently become party policy.

I have resigned from Scottish Labour's shadow cabinet. I feel this is the only way I can effectively represent my constituents views on Europe and that we must make every effort to ensure the UK remains in the EU. pic.twitter.com/3nruDpaiXS — Daniel Johnson MSP (@DJohnsonMSP) May 28, 2019

Johnson said 80% of his constituency backed remain in 2016 and 20,000 of those had signed a petition to revoke article 50. “Quite simply, I do not feel I can represent my constituents effectively unless I can articulate and represent this view,” he said.

That in turn forced Leonard into agreeing to a second emergency meeting on Tuesday evening, when the party’s centrists pressed for further concessions, including an immediate adoption of a second referendum as Scottish party policy. There were suggestions some are considering options for challenging Leonard’s leadership.

Findlay, who had played a key role in Corbyn’s leadership election campaigns in Scotland, also said he was leaving Holyrood at the 2021 election. There are suspicions his decision to quit was linked to the failure of Corbyn’s strategy on Brexit.

“There is a big world outside the Holyrood bubble. Life is too short to be involved in endless internal battles with people who are supposed to be on the same side,” Findlay tweeted.

Today I resigned from my positions in the Scottish Labour Party -I will stand down from parliament at the election - there is a big world outside the Holyrood bubble, life is too short to be involved in endless internal battles with people who are supposed to be on the same side pic.twitter.com/j3MBEIfm6D — Neil Findlay MSP (@NeilFindlay_MSP) May 28, 2019

Leonard told reporters after the first meeting he had no plans to resign but he admitted last week’s election result was “incredibly bad”. He added: “I’m taking the flak – I’m prepared to take the flak for what was a poor result.”

His internal critics believe Leonard is entirely to blame for backing Corbyn’s Brexit strategy even though Scottish voters are far less hostile to the EU. They had told Leonard the Scottish party should have been far more open to a second referendum from an earlier stage and have called for less centralised policymaking.

In the event, the Scottish National party’s support jumped by nearly 10 points to 38% and it won three of Scotland’s six European seats, chiefly at Labour’s expense. Scottish Labour’s vote fell to 9.3%, its worst election result since 1910.

Leonard, however, said his late conversion to backing a second referendum was due to the situation in Westminster and UK-wide.

“In light of the failure of the Labour frontbench and Tory frontbench talks, in light of the Brexit party’s upsurge in the elections on Thursday and in light of Theresa May’s decision to step down, and there now being a Tory leadership race, it is clear to me that the threat we now face is from a no-deal Brexit,” he said.

“And under any circumstances, I believe there should be a confirmatory referendum on a credible leave deal and a credible remain deal.”

That position was backed by Alex Rowley, a former Scottish Labour deputy leader, who is a Corbyn loyalist, who said: “People have been lied to over Brexit. We’ve seen the Tories have made such a mess of it the last three years, so we need to get to a position where the people are able to decide again to ratify the agreement or not. The people need to decide.”