Tory backbencher Andrew Tyrie has spoken out against plans to require 55% of MPs to vote for dissolving Parliament, predicting it would face opposition in the Lords.
Peers would see the move as an "arbitrary fix" designed to "bolster" the coalition, the MP for Chichester said.
They would seek to "carve it up" unless it was subjected to pre-legislative scrutiny, he added.
Mr Tyrie also argued for a sunset clause, saying he could not see why it should remain in place after the current arrangement had come to an end.
"My instinct would be to try and ensure fixed-term parliaments with something less radical," he added.
DUP spokesman William McCrea also opposed the 55% rule, saying: "We must do nothing that diminishes the authority of parliament."
Watch the first half of the debate