Blair has been accused of being too presidential
Andrew Mackinlay, one of the outspoken MPs elected to the Labour Party's parliamentary committee, vowed to challenge Downing Street's "White House" tendency.
Coming in the wake of Monday's first Commons defeat for Mr Blair's government since he took office four years ago, the rebels' election is another indication that Labour MPs are now more willing to take on ministers.
More than 100 Labour MPs rebelled to inflict defeat on the government over its decision to sack Gwyneth Dunwoody and Donald Anderson as the chairs of two Commons select committees.
Key committee
Five of the six MPs whose election to the committee was confirmed on Wednesday took part in that rebellion and one of them, Gordon Prentice, helped to mastermind the defeat.
He and Mr Mackinlay are joined by former ministers Chris Mullin and Tony Lloyd, former frontbencher Ann Clwyd and MP Helen Jackson as newly-elected members of the committee.
The election of Mr Prentice, Mr Lloyd and Ms Clwyd, all of whom are unafraid of publicly disagreeing with ministers, is another sign of Labour backbenchers' unwillingness to be taken for granted in Mr Blair's second term as prime minister.
And few expect Mr Mullin, who asked the prime minister to return to the back benches following his spell as a junior minister, to be unquestioningly loyal.
The committee will meet Mr Blair twice a week to discuss Labour Party issues.
After the results were confirmed at the regular meeting of the Parliamentary Labour Party on Wednesday, Mr Mackinlay said: "There is a sea change going on and this is reflected in this election.
"There is a mood for this change and this is a critical moment because decisions are being taken, detailed decisions, over the summer on issues such as the membership of select committees and it is important that we feed into that.
Mr Mackinlay called the vote on select committees a "watershed" and said Robin Cook now had the chance to be a "real reforming" Commons leader.
"There is a need for candour. In my view the problem is the prime minister often is surrounded by people who tell him what they think he would like to hear, rather than speaking with sufficient candour.
"That's one of the consequences of Number 10 developing into a sort of White House."
Signs of conflict
The opening weeks of Mr Blair's new government have already pointed to possible conflicts within the labour movement in the months ahead.
As well as Monday's unprecedented Commons defeat for Mr Blair, trade union leaders have threatened trouble over plans to involve private companies more in public services.
That row has spurred the GMB union into deciding to cut its donations to the Labour Party by up to £1m over the next four years.