Tory leadership hopeful David Cameron says he would not let disgraced peer Jeffrey Archer retake the party whip in the Lords if he becomes leader.
Lord Archer was jailed for perjury
Lord Archer, who was banned in 2000 because he perjured himself in a libel case, has applied to rejoin the party.
He is also reported to have asked the Chief Whip about re-joining the Conservative benches in the Lords.
Shadow transport secretary Alan Duncan said the party should readmit him as the time for condemnation was over.
Lord Archer was jailed in 2001 for perjury after he was convicted of making up a false alibi in a 1987 libel case. He served two years of a four year sentence.
His application to rejoin his local party in Cambridgeshire and rejoin the party in the Lords has had a mixed reaction.
Leadership favourite Mr Cameron said Lord Archer's membership application should go through the "normal processes".
However, he added: " I think that his days as a front line politician are over."
He said: "The thing that would be in my control if I was leader of the party, would be whether he would be able to take the whip in the House of Lords and I'm clear he shouldn't do that.
"I think it wouldn't be appropriate and I think that I should be able to decide who's going to be on the front line."
Mr Cameron's rival for the top job, David Davis, has not commented on the issue.
Mr Duncan said: "I think anyone from any background and any experience is allowed to have political opinions. If he joins his local party - well, I'm glad anyone who thinks about life is a Conservative rather than a socialist."
But former Conservative minister David Mellor said it would be a mistake to allow Lord Archer to return to the Tory benches in the Lords.
'Game is up'
He told BBC News: "It is difficult enough to take the House of Lords seriously without having people who have served substantial prison terms going back in and participating in their debates.
"One day open prison, next day legislating, it is just not a very sensible basis for British public life to be conducted."
He added that Lord Archer should "just bow out gracefully".
He added: "Jeffrey is one of those chaps who doesn't understand when the game is up."
The Conservative party's head office has confirmed Lord Archer has made an application to rejoin the party in Cambridgeshire, where the peer has a country home.
However, this has not yet been processed, a spokesman said.
On Saturday, party officials dismissed a report that Lord Archer had rejoined his local constituency association in Vauxhall, south London where he also has a luxury penthouse apartment.
Lord Archer had been a senior Conservative
But Lady Archer later insisted her husband's application had been successful.
"His application to Vauxhall has been accepted," she said. "He is still waiting to hear back from South Cambridgeshire."
Lord Archer nearly lost his seat in 2003 when the government planned to extend rules banning MPs who have served more than two years' imprisonment to peers.
But the plans were shelved at the last minute.
The former deputy party chairman has raised millions of pounds for the Conservative Party and stood as its candidate for the high profile job as London mayor.
But he was forced to withdraw from the race in 2000 when it emerged he had lied in his 1986 High Court libel trial against the Daily Star.
He had wrongly won £500,000 in damages from the newspaper.