The House of Lords is ready to “put up a real fight” over plans to replace it with a mainly-elected chamber, Midland peer Lord Cormack has warned.

Conservative peer Lord Cormack, former MP for South Staffordshire, urged the government to scrap plans for a new second chamber in which 80 per cent of members were elected.

He is one of a number of West Midlands Conservative politicians to speak out against the government’s planned Lords reforms.

David Cameron faces being caught in a battle between Conservatives opposed to the planned changes and his Liberal Democrat coalition partners, who insist on reforms.

Lib Dems are also opposed to holding a referendum on Lords reforms, arguing that none is needed, while some Conservatives believe a referendum would be essential.

A planned Bill to introduce “a mainly elected chamber” was included in the Queen’s Speech. The government is still working on the details, but these will be based on the findings of a Parliamentary inquiry which recommended around 450 peers should be elected using a form of proportional representation.

A city the size of Birmingham would be likely to elect six or seven peers, with the entire city voting as a single constituency and seats allocated to the parties in proportion to the votes they receive.

Speaking in the House of Lords itself, Lord Cormack warned that an elected second chamber would come into conflict with the House of Commons, because both politicians in both Houses of Parliament would believe they had a mandate.

And he warned that voters in a referendum would oppose the changes – just as Birmingham voters opposed a mayor in the city’s referendum on May 3.

He said: “In the second city of our land, Birmingham, candidates were already lining up but the people said, ‘Hold on a minute – we don’t want that’.

“I think that they would say much the same in a referendum on the future of this place, but I hope that it does not come to that.”

He added: “We have got to be prepared to put up a real fight if it is necessary, but I beg of my noble friend on the front bench that it will not be necessary so that we can reform this institution constructively and properly without creating unnecessary competition with the other end of the corridor, creating a House that is not complementary but in conflict, because that is what we would do.”

At the same time, some opponents of Lords reform are insisting that a referendum would be needed if the Government does press ahead with such a radical change. Hereford MP Jesse Norman (Hereford and South Herefordshire, Con) placed the Prime Minister on the spot as the Commons debated the Queen’s Speech.

He asked: “Does the Prime Minister share my view that since a consensus has not proved to be available, Lords reform cannot be a priority now, and does he also share my view that any measures presented to this House should be put to the people in a referendum?”

Mr Cameron insisted: “Reforming the House of Lords is not the most important priority for the Government – that is dealing with the deficit, getting our economy moving, increasing the level of responsibility in our society and getting on the side of hard-working people.

“Those are the things that matter the most, but I think it is perfectly possible for Parliament to do more than two things at the same time.”

Later, he also appeared to rule out a referendum, saying: “Every political party went into the election with a pledge to reform the House of Lords so I do not personally see a referendum as having much to recommend it.”

But Mr Cameron did appear to hint that the government might abandon the plan – using Labour’s opposition to the plans as justification. Labour backs change, but argues that every member of the second chamber must be elected, not just 80 per cent, and also insists that a referendum is needed. Birmingham peer Lord Hunt of Kings Heath, Labour’s Deputy Leader in the Lords, has been leading opposition to the government’s plans.

Mr Cameron told the Commons: “At the last election, all political parties put forward in their manifestos proposals for a partly, or mainly, elected House of Lords, but let me say this: this is only going to proceed if the political parties will agree to work together and take a responsible attitude towards this reform.”

Stratford MP Nadhim Zahawi has also emerged as a leading opponent of Lords reform on the Conservative benches, warning that an elected second chamber would “dilute the primacy of the Commons” and lead to “legislative deadlock”.

The Warwickshire MP, a co-founder and former CEO of polling company YouGov, last month presented the results of private polling to a meeting of backbench Conservative MPs, showing that exactly zero per cent of people said that House of Lords or political reform should be the government’s main priority for the next year.

Lib Dem MP Lorely Burt (Solihull), who supports Lords reform, attacked calls for a referendum. She said: “Given that it was in every party’s manifesto, I can’t see why a referendum is needed.

“In practice, people who don’t want reform are calling for referendums as a way of trying to get it delayed or scrapped.”