The government has been accused of trying to avoid scrutiny of its Brexit strategy by creating a parliamentary committee that is too big to do its job properly.
Under a plan to be unveiled on Wednesday, 21 MPs from every party in the House of Commons except Ukip and the Greens, will sit on the new Brexit select committee.
The committee will be almost double the size of almost every other Commons select committee after a deal struck between Conservative and Labour whips.
But some senior MPs have claimed that the committee has been made deliberately large so that it is less effective at scrutinising the government’s strategy and less able to reach a consensus.
Their view has been echoed by the Whitehall thinktank the Institute for Government (IFG) that warned it could be a “recipe for the lowest common denominator”.
“The more MPs you have on a committee the harder it is to get a persistent and effective form of question and the harder it is to reach a consensus in your conclusions,” said Hannah White, the IFG’s director of research. “On such a contentious issue as Brexit there is a real risk that such a committee just become a recipe for the lowest common denominator.”
A senior Conservative MP added: “It’s ridiculously large. It won’t be able to agree anything and you can’t help but feel it’s a bit of a conspiracy by our whips to make sure the government get on with it all without scrutiny or criticism.”
Elections among MPs for membership of the new committee are due to take place next week. It will be chaired by a Labour MP with the pro-remain former shadow foreign secretary, Hilary Benn, seen as the front runner.
However he is expected to be challenged by the leave supporter Kate Hoey. If she secures enough nominations she could defeat Benn if the government and Brexit-supporting Tories decide to throw their weight behind her candidacy.
Other MPs thought likely to seek positions on the committee include the former Brexit-supporting ministers Michael Gove and Iain Duncan Smith.
From the remain side, the former business minister Anna Soubry and former shadow housing minister Emma Reynolds are also thought to be intending to put their names forward.
Soubry said the committee did seem “very big” but added: “If Hilary Benn chairs it he will no doubt make sure it works effectively.”
Most Commons select committees that scrutinise the work of government departments have no more than 11 members. The exceptions are the public accounts committee, which has 15, and the liaison committee – which is made up of the chairs of all 31 of the select committees and regularly questions the prime minister.
That committee has faced accusations from MPs that it is “toothless” due to its size and “skims over” subjects to fit in more questions. Under its current chair, Andrew Tyrie, efforts have been made to limit the range of questions at each session to make it more effective.
The Brexit committee will have a wide remit to scrutinise the government’s strategy for exiting the European Union and the work of David Davis’s new department. Ten members will be Conservative, five Labour, two SNP and one seat each for the Liberal Democrats, the Democratic Unionist party, the Social Democratic and Labour party and Plaid Cymru.
Elections for the committee chair and membership are due to take place next week. There will also be a new select committee shadowing the work of the new department for international trade. It will be chaired by the SNP MP Angus McNeil.
