Kate Forbes has made it through to the final run-off in the race to replace Nicola Sturgeon as SNP leader despite the furore caused by her stance on equal marriage.

The Scottish finance secretary will face Humza Yousaf and Ash Regan in a three-horse race to become first minister.

All three made it on to the ballot paper after nominations closed on Friday.

In a separate boost for Forbes, a new poll showed she is the most popular candidate among SNP supporters.

Forbes’s campaign got off to a rocky start after she gave a series of interviews in which she set out her strict religious views.

She revealed that she would have voted against equal marriage had she been an MSP when the law was passed, and that she believed having children outside of marriage was “wrong”.

While Forbes made clear her beliefs were personal and that she would defend any existing rights, her views led to a number of her colleagues withdrawing their support.

She later said she had felt “greatly burdened” by the hurt caused by her media responses, but also questioned whether Scotland had become “so illiberal that we cannot have these discussions”.

According to the poll of SNP members, 28% said they would back Forbes, followed by 20% for Yousaf and 7% for Regan.

The poll, carried out for communications agency the Big Partnership, involved 1,001 Scots who voted SNP in 2021. They were questioned between Monday and Wednesday this week.

It also found that only 5% of SNP supporters think the new leader’s faith or personal beliefs are important, while almost a third still did not know who to back.

This morning, Regan officially launched her campaign with a pledge that under her leadership, every election – either at Holyrood or Westminster – would be treated as a de facto independence referendum.

In an interview with the Herald, she said the SNP had “dismantled” the Yes movement since the independence referendum and that she wanted to give it “back to the people” so the Scottish government can focus on running the country.

Regan was thrust into the limelight earlier this year when she resigned from government in opposition to Sturgeon’s controversial gender reform bill, which has been blocked by Westminster. She has vowed to drop the reforms if she is elected.

Forbes also confirmed that she would not have voted for the government’s gender reforms had she not been on maternity leave when the vote was passed.

The issue separates Regan and Forbes from Yousaf, who is a vocal supporter of trans rights and is largely considered to be the favoured “continuity Sturgeon” candidate.

However, the health secretary has come under fire after he was accused of deliberately missing the vote to legalise gay marriage by setting up a “diary clash” for the same day.

In comments reported by the Independent, Labour’s shadow health secretary Wes Streeting claimed it was “common knowledge” that Yousaf was in parliament for the day of the vote.

“It’s all very well being courageous about equality when the battle has been fought and won,” Streeting said. “But where were you, Hamsa, when the battle was ongoing?

“It is perfectly reasonable to ask Yousaf if he supports equal marriage, as he says he does, “why did you abstain in the vote?” — when everyone knows he was in the Scottish parliament that day.”

In response, Yousaf told ITV he missed the vote “for good reason” after he had a meeting with the Pakistan consulate over the case of a Scottish citizen on death row.

He also told Sky News that the issue had been “resurrected” to undermine his position in the leadership contest.

Following the close of nominations, SNP members will take part in a postal vote to choose their next leader, with the winner announced on March 27.