Anti-Iraq war MP George Galloway has been accused of arrogance and self-interest for taking part in the Celebrity Big Brother contest.
Actress Helen Mirren, who campaigned against Mr Galloway at the general election, accused him of self-interest.
Minister for London Jim Fitzpatrick said: "I am not too surprised about it, as Mr Galloway is a C-list politician with an A-list ego."
Mr Galloway insists his decision to be a contestant is good for politics.
"I believe that politicians should use every opportunity to communicate with people," he said in a statement.
"I'm a great believer in the democratic process. Big Brother is watched by millions.
"More young people vote during Big Brother than in the general election. I hope they'll all be voting for me over the next few weeks."
TV studios first?
He joins celebrities such as former game show host Michael Barrymore, Faria Alam, who had an affair with England coach Sven-Goran Eriksson, US basketball star Dennis Rodman and model Jodie Marsh.
Oscar-nominated actress Ms Mirren, a constituent of Mr Galloway's in Bethnal Green and Bow, who backed his Labour rival Oona King during the general election, described his decision to go on the show as "very weird".
"Where does this guy's ambition go? That's very peculiar," she said. "I think he's a very disturbing person, I think he's a very disturbing politician. Personally, I feel his interest is a self-interest."
And Mr Fitzpatrick said: "But while he has chosen to lock himself away in this celebrity graveyard, his constituents have yet again been left without help for their problems and without a voice in their Parliament.
"For an elected parliamentarian, who is paid from the public purse, to shirk responsibility in this way is as arrogant as it is exploitative."
That criticism was echoed by Labour peer Lord Foulkes, who said Mr Galloway appeared to "prefer the TV studios to the chamber of the House of Commons".
Teetotal Mr Galloway was thrown out of the Labour Party for inciting Arabs to fight British troops, inciting British troops in Iraq and threatening to stand against Labour in an election.
But when his Glasgow Kelvin seat was abolished in boundary changes, he won in Bethnal Green and Bow for the Respect coalition.
The MP was met with boos from the crowd as the show began on Thursday night.
As he joined the show, he joked: "Tony Blair will be in a dilemma. One part of him will want me to be evicted early so I don't score another victory.
"On the other hand, as long as I'm in there, I'm leaving him alone. That's going to be a dilemma for those that don't like me.
"Do they want me locked up in the Big Brother house, or do they want me at large and let loose on the streets?
"I'm not a politician of your ordinary type. Most politicians - and most politics - are boring.... I don't think I am boring.
"They say that politics is show business for ugly people, but as I always crack, what would I know about that? I like a challenge."
As he entered the house, Mr Galloway shouted "Stop the war" and made a peace sign.
He introduced himself to fellow contestants saying: "George Galloway, I'm a member of Parliament."
And he was soon seen chatting to actress Rula Lenska about a mutual friend whom he knew from the Nicaraguan Solidarity campaign.
Mr Galloway listed his pet hates as "drunkenness, bad manners, bigotry and ignorance".
Presenter Davina McCall said the MP's main loves in life are "his daughter, sunbathing and sex".