North West Norfolk candidate Manish Sood hit out at Mr Brown less than 48 hours before the polls open.
Today, Mr Sood, speaking at his home in Leicester, described himself as a "freedom fighter" and said: "I will stand by what I say because I know it's the truth and nothing but the truth.
"All I'm trying to do is bring back the true Labour policies we had under Michael Foot. We have a Prime Minister who is incompetent, who doesn't know what he is talking about, who is not clear on his policies and the problems are getting bigger in terms of the bureaucracy."
He added: "If you can't do the job properly then somebody like me will need to go in and clean up the system. It's as simple as that."
Mr Sood first claimed Gordon Brown had been "the worst Prime Minister we have had in this country" in an interview with the Lynn News newspaper.
His claims prompted the local Labour Party to disown him, dismissing him as a "dreadful candidate".
Mr Sood's own mother, a Labour councillor in Leicester and former Lord Mayor of the city, also voiced her anger about his comments today.
Manjula Sood said: "My late husband gave his life to the Labour Party and my loyalty is to the party and to what Gordon Brown has done for the country.
"My son holds his own views but I'm very angry about this and very angry with him."
Mr Sood said he had not spoken to his mother today, and said she "probably isn't speaking to me", but he said he stood by his criticisms of the Labour Party.
"If they are not going to listen, I'm going to carry on saying what I'm saying because they are damaging the country," he added.
"He is the Prime Minister that got elected without having a vote.
"With Tony Blair there was a proper majority, with Margaret Thatcher there was a proper majority.
"My motive is to clean up the system, to make Great Britain the best country in the world."
He said he wanted to see less crime, more power for police, prison wardens and trade unions, tighter controls on immigration and the return of the death penalty.
"People have lost respect for being British and being part of this system and part of this country," he said.
"All I'm saying to Gordon Brown is we need to go back to the basics and back to what the Labour Party was in the '60s and '70s.
"What I am saying is the right truth and nothing but the truth and as a result people have become too spoiled, too used to the system and too used to the bureaucracy, the corruption. I'm trying to improve the system.
"I am a true staunch Labour Party member, my policies fit in very well with the party, it's just they can't accept it because they have been too used to the modern-day thinking.
"My policies fall back to the history of the party in the '60s and '70s and the way I was taught by my dad and my grandad.
"I have still got an uphill battle ahead of me but I never give up. I'm a freedom fighter and I will continue because I am proud of being British and I want my country to be the best country in the world."
Justice Secretary Jack Straw condemned Mr Sood's views as "completely maverick".
On BBC Radio 4's World at One programme, he said: "He's been disowned by his own party and, I gather, by his mother.
"You get this at every election. I don't think it's a matter of any purport at all."
Mr Sood faced censure from the local Labour Party in North West Norfolk.
Chairman David Collis said: "Manish Sood does not represent the views of North West Norfolk Labour Party members.
"Manish has been divorced from this campaign for some time but clearly determined to get as much attention for himself as possible.
"Despite having such a dreadful candidate, loyal Labour members will continue to put the case for Gordon Brown as the best man to take Britain forward.
"We are fully in support of Gordon Brown as leader of our party and of the excellent campaign he is running."
A party source said the CLP had considered deselecting Mr Sood on several occasions in the past but had decided it "wasn't worth the effort", given the large Tory majority.
Mr Sood was likely to face a motion of censure at the next meeting of the CLP after the election, the source added.
The Prime Minister brushed off the comments when asked about them in Leamington Spa, telling Five News in a pre-recorded interview: "We are fighting an election campaign and we are fighting to the finish."
He added: "I'm not going to get into any other issues than the issues of this election. I think it's for the electorate to judge.
"I'm not going to get diverted from looking at the policy issues."
In the constituency, Liberal Democrat candidate William Summers said the comments showed the contest was now a "two-horse race".
Tory Henry Bellingham, a shadow justice minister, was returned to North West Norfolk in 2005 with a majority of 9,180.
Mr Summers said there had been a "notable shift on the doorstep" with many lifelong Labour voters switching allegiance to the Lib Dems.
He said: "It highlights the frustration that many people have got with Labour - even their own candidates are feeling frustrated.
"This is a two-horse race between the Liberal Democrats and the Tories and the only way to a fairer Britain is through the Lib Dems."
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