Keir Starmer has said Boris Johnson will not be worthy of an honour when he leaves Downing Street - but insisted it was right that Tony Blair received a knighthood.
The Labour leader accused Mr Johnson of treating politics as a "branch of the entertainment industry" in a major New Year's speech, where he said the Prime Minister believed the rules don't apply to him.
Mr Starmer said the PM would not be worthy of eventually being honoured by the Queen amid a row over whether Sir Tony should have been appointed as a Knight Companion of the Most Noble Order of the Garter in the New Year Honour's list.
More than 500,000 people have signed a petition for Labour's longest serving PM to be stripped of the accolade, which has been previously bestowed on former premiers.
The honour, which is awarded by the Queen rather than on the advice of the Government, has led to a backlash, with critics pointing to Sir Tony's decision to take Britain to war in Iraq.
Asked by the Mirror if he thought Mr Johnson should eventually get an honour, he said: "No I'm sorry, I do not think that this Prime Minister has earned the right to have an honour.
"I do think Tony Blair has."
Asked if the PM thinks he deserves to be Sir Boris after he leaves office, his spokesman said: “That would be a matter entirely for Her Majesty the Queen.”
Mr Starmer earlier told GMB it was not a "thorny issue" for the former Labour leader to receive the honour.
“I think Tony Blair deserves the honour," he said.
“He won three elections, he was a very successful Prime Minister.
“I haven’t got time this morning to list all of his many achievements which I think vastly improved our country - minimum wage, Sure Start for young families.
“But the one I would pick out in particular is the work he did in Northern Ireland, and the peace process, and the huge change that has made.”
In his speech in Birmingham, he name-checked Mr Blair alongside former leaders Clement Attlee and Harold Wilson as he set out a new contract for the British people.
Asked why he failed to mention his predecessor Jeremy Corbyn, he said: "I don't apologise for mentioning Attlee, Wilson and Blair. The thing that unites those three very different prime ministers is that they all won.
"They all won. They introduced Labour governments that changed Britain for the better and I want to be the fourth in that list writing the next chapter of our history.
"So, I have always cited Attlee, Wilson and Blair precisely because they won. And unless the Labour Party is absolutely clear that our whole purpose as a party is to win power to govern to change the lives of millions of people, then we will be talking politics and not doing politics. So, no apology about that at all."
Mr Starmer promised "straight leadership" based on the values of "security, prosperity and respect" if Labour wins the next election.
He said the Tories had lost the trust of the voters at a time when it was "a matter of life and death" for the people.
In a swipe at Mr Johnson, he said: "I don’t think politics is a branch of the entertainment industry.
"I think it’s the serious business of getting things done...We have a Prime Minister who thinks the rules apply to anyone but him.
"Just when trust in government has become a matter of life and death, for the Prime Minister it has become a matter of what he can get away with."
He said the problem lay with the Tory party rather than with the PM.
"This is not just about the flaws of one individual," he said.
"It’s about the flaws of a whole style of government, the flaws of an ideology, of a political party that has been in power too long."
