Laura Pidcock, who was tipped as a successor to Mr Corbyn before losing her seat at the election, said the former prime minister’s legacy “hangs around this party like a millstone”.
She claimed that voters in her constituency, which was won by the Tories, had often cited Mr Blair as a reason for not voting for her.
Ms Pidcock was defending a majority of 8,792 in the North East Durham constituency, which had held by Labour since 1950, but lost out after a major swing to the Conservatives.
The lowest majority held by a Labour MP in the constituency during Mr Blair’s time as leader was 13,443.
Ms Pidcock posted on Twitter: “Vital to learn the lessons of Labour’s [general election] defeat. However, the answers will not be found at the door of New Labour’s architects. Blair’s legacy still hangs around this party like a millstone, especially in the North East. I heard it time and time again.”
Her post was shared by her former chief of staff, Ben Sellers, who wrote: “Absolutely bang on. The really hilarious thing is propagandists for the New Labour project, laying into the members [of] Labour as it stands, thinking that we were born yesterday. We know they want to take us back. It’s not happening, not with 500,000 of us. Sorry about that.”
He said that mistakes had been made under Mr Corbyn but that “some of the longer term causes of our defeat were down to New Labour and Blair’s record”.
Ms Pidcock was responding to an article by Mr Blair in which he warned that Labour must “renew itself as the serious, progressive, non-conservative competitor for power in British politics” or else “retreat from such an ambition, in which case it will be replaced”.
Her comment drew mockery from other former Labour MPs.
Tom Blenkinsop, the MP for Middlesbrough South and East Cleveland until 2017, wrote: “Safe Parliamentary seat lost 2019. Safe Northumberland council seat lost 2017. All under Corbyn’s period of leadership….bloody Tony Blair!”
Former Copeland MP Jamie Reed asked: “Have you learned nothing Laura?”
Polls suggest that Mr Corbyn was the biggest reason for former Labour voters abandoning the party. Thirty-seven per cent of Labour defectors mentioned the party leadership, while 21 per cent cited the party’s Brexit policy and 6 per cent did not like its economic agenda.