Douglas Ross has claimed Boris Johnson is "fit for office" despite saying earlier this year that his position as Prime Minister was "no longer tenable".
The Scottish Conservative leader has backed his boss after he faced criticism over his handling of the cost of living crisis and partygate.
Johnson has been under pressure in recent weeks after he - along with his wife Carrie Johnson and Chancellor Rishi Sunak - received a fine for one of the gatherings.
Ross, an MP for Moray, previously called on the Prime Minister to quit before the Russian invasion of Ukraine.
He submitted a letter to the backbench 1922 Committee pushing for a vote of no confidence in the Prime Minister, but has since rescinded it.
Ross was asked by the Scotsman if Johnson was fit for office.
He replied: "Yes, because he is leading the UK response to this crisis at the moment.
"But that doesn't in any way diminish what he did and the actions that have been taken by those who investigate it.
"He is fit for office to continue with what the UK Government have done, his Government has done, to help the people of Ukraine.
"That's not just me saying it, that's President (Volodymyr Zelensky) who singled out Boris Johnson as a Western leader who has provided some of the greatest support.
"That relationship I don't believe should just be cut off because clearly President Zelensky and the people of Ukraine welcome the support they've had from the Prime Minister and the UK Government."
In January when he called for Johnson to resign over partygate, he said: "Regretfully I have to say his position is no longer tenable.
"I didn't want to be in this position, but I am in the position now where I don't think he can continue as leader of the Conservatives."
He was asked: "If he was at the party he can’t continue as Prime Minister, can he?”
Ross replied: “No - because it's a breach of the guidance. It's a breach of the rules that was put in place. It's also breaking the law."
Now, Ross said he had not seen anything that would "change his mind" on the Prime Minister's position to remain in place.
"Would it have been credible for me to have kept my letter in if at the same time I was saying 'we have to be united in standing with the people of Ukraine', in the same way that Keir Starmer said as the conflict started now wasn't the time to replace the Prime Minister," he said.
"(SNP Westminster leader) Ian Blackford stood up in the House of Commons and called for unity. I agreed with them when they said that.
"I just haven't seen anything to change my mind that has potentially changed theirs."
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