A close ally of Boris Johnson has said he should not be written off as he hinted at a potential return to frontline politics for the PM in the future.
Lord Edward Lister was asked on Sky News' Sophy Ridge on Sunday about reports some MPs were experiencing "seller's remorse" over Mr Johnson's departure and want him to make a comeback.
Lord Lister said his colleagues "overreacted" to the scandals that led to the outgoing prime minister's downfall, and it was wrong to get rid of him.
He said Mr Johnson was "the best prime minister we've had", adding: "I think he would continue to be a good prime minister. I think he would be very successful in a further general election."
When asked if he might be tempted to make a comeback, Lord Lister said: "Well, maybe in the future, I'd never say never on anything with Boris Johnson, anything is possible in the future."
He said, "for now, we have a new leader" and the party must get behind whoever that will be - either Liz Truss or Rishi Sunak.
However, when pressed on whether Mr Johnson may try to return "if the ball comes loose at the top of the scrum", Lord Lister said: "Well, he is an amazing person. He is full of energy. He works extremely hard.
"He is going to be watching all this, and if something happens in the future, as you said, and the ball comes loose in the scrum, then anything can happen.
"I'm not going to predict, all I'm saying is I would never write him off."
It was reported in the Sunday Mirror that at least 12 Tory MPs are plotting to bring Mr Johnson back by Christmas by submitting no confidence letters in the new leader, who is expected to be Ms Truss.
However, writing in the Sunday Express, Mr Johnson urged the party to move forward and unite behind whoever replaces him, as he backed both of the candidates' abilities.
Johnson comeback 'a fantasy'
Meanwhile, former chancellor Lord Philip Hammond dismissed the idea of a political comeback as a "fantasy" as he hit out at Mr Johnson's record as prime minister.
He told Sophy Ridge: "I think this is fantasy. I think Boris has not been a good prime minister, I think he's damaged the office of prime minister, I think he's damaged the Tory party.
"I think Boris will no doubt have a very successful career in other fields in the future, and I think he should move on and put aside any idea of hanging like a malevolent shadow over the next government."
Senior Tory MP David Davis also laughed off the idea of a Johnson comeback, saying those rumours "are probably coming from the Boris Johnson camp".
He said that if the mass exodus of ministers hadn't forced him to resign then "the very next week, the party would have held a no confidence vote in him".
"He lost the confidence of the party, and I don't think he'll get that back in a hurry," Mr Davis said.
A Labour frontbencher also ridiculed the idea.
Nick Thomas-Symonds, shadow minister for international trade, said: "It really does show the depths to which the Conservative Party has sunk and the fact they are so tired after 12 years in office.
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"That they've just ousted a leader after his flagrant disregard for COVID rules, after he showed, time and again, it was one rule for him and another rule for the rest of the population.
"It really does show now the Conservative Party has completely lost its way if they are saying credibly that they want to get rid of one leader, then try to have a leadership contest with others, then try and bring the other leader back."
The nation will find out on Monday if Liz Truss or Rishi Sunak will be handed the keys to Number 10.
The winner will officially take over on Tuesday, when Mr Johnson and his successor will travel to Balmoral in Scotland to meet the Queen.
Ms Truss has been ahead in the polls throughout the leadership race, and is widely expected to become the next prime minister.