Andrew Mitchell will have a difficult time as Chief Whip after a row over whether he called Downing Street police officers "plebs" or not, Tory MP David Davis has warned.
Mr Davis, who ran against David Cameron for the leadership of Conservative Party in 2005, said: "He will have a difficult time.
"What does a Chief Whip have at his fingertips to deploy normally? Well, a mixture of charm, rewards, appeals to loyalty - all of those are diluted at the moment."
Mr Mitchell has pulled out of the Conservative Party conference in Birmingham despite being the city's only Tory MP so as to avoid being a "distraction."
He was previously tasked with running Mr Davis's campaign against David Cameron. Mr Davis defended Mitchell in Parliament's House magazine but said he had a "very, very difficult" task ahead of him.
"Andrew is a clever lad, a capable character who's been a whip before. He's experienced, he's been through hard times in government before. If he asks for my advice, I'll give it," Davis said.
"There are very few jobs to be given out. They are going to have to steer the Parliamentary party through a time when it is not at all clear that our allies are still going to be our allies. It's going to be very, very difficult.
In the same interview, Mr Davis urged the Prime Minister to "have a plan" on Europe.
He said: "The Europe Minister, the Foreign Secretary and the Prime Minister have got to have a plan. At the moment I don't have a feeling that the party or the Government knows explicitly where it's going.
"The explicit answer to the European issue, whether it's eurozone or the more general European membership issue, is a big renegotiation and multiple referendums."
Commenting on the risks posed by Ukip to the Conservatives, David Davis said: "Ukip's appeal is not just about Europe. They basically present themselves as an alternative Conservative party. Whether it's law and order or whether it's green policy. It's like a Conservative primer. We want to watch it."