Viscount Cranborne said any efforts to wreck the House of Lords Bill would be against the Salisbury Convention under which peers do not vote against the governing party's manifesto pledges.
He hinted that any Tory revolts would also diminish chances to adopt the so-called Weatherill amendment, which would retain 92 hereditaries during the interim period of reform.
Speaking during the Bill's committee stage, Lord Cranborne, one of the deal's architects, said: "If you pass an amendment which would in effect wreck this Bill, it would send very clearly a pattern for the remainder of this debate, which will make it increasingly difficult to amend the Bill in other ways."
But Lord Campbell of Alloway, a Tory peer, insisted the Government should delay the legislation unless it won the support of the public in a referendum.
Earlier, Lord Strathclyde, the Tory leader of the Lords, indicated he could not rule out a legal challenge to the Bill from hereditary peers, doubting the strength of support by peers for the Weatherill amendment, which is to be debated next week.
"Some peers think there may be a bribe in it and don't want to be involved.
He continued: "Others think the Bill is monstrous and the only thing to do is to kill it stone dead and, if that means going to the Parliament Act, so be it."Reuse content