The Government expects to overturn last night's defeat in the House of Lords on voting reform when the Bill returns to the Commons, Prime Minister David Cameron's spokesman said today.
Peers voted by a majority of just one to require turnout of 40% in the upcoming referendum on the Alternative Vote system if the result is to be binding on the Government.
The vote is another fly in the ointment for ministers who must get the legislation on to the statute book before Parliament rises for its half-term break on February 16 if the referendum is to be held as planned on May 5.
But Cabinet was told at its regular weekly meeting this morning that the Parliamentary Voting Systems and Constituencies Bill remains "on track" to meet the deadline, and Mr Cameron's spokesman insisted that it was still the PM's intention to go ahead with the original timetable for the vote.
Voters will be asked whether they want to keep the traditional first-past-the-post system for electing MPs by marking a cross next to their favoured candidate, or switch to AV, under which candidates are ranked in order of preference.
Last night's Lords amendment would make the result binding if turnout was more than 40%, but leave the decision to Parliament if fewer voters took part. A similar "threshold" arrangement led to the failure in 1978 of the then Labour government's plans for Scottish devolution.
A majority of Labour peers voted for the threshold, even though the party opposed it in the Commons, where it was rejected by 549 votes to 31.
Mr Cameron's spokesman said today: "There was a consensus view across parties on this issue in the House of Commons, so no doubt the Commons will want to take a view on it.
"This (threshold) was not part of our original proposals and you would not expect us to want it to stay in the Bill.
"I would expect it to be amended back when it comes back to the Commons."