Nick Clegg has warned peers not to "over-romanticise" the House of Lords as he faced down critics of his plans to create an elected chamber.
Appearing before a committee of MPs and peers on Monday afternoon the deputy prime minister confirmed he would use the Parliament Act to force the legislation through if the current House of Lords chose to object. The Act gives the elected House of Commons the power to overrule objections from the unelected Lords.
Under government proposals the current House of Lords would be replaced with a 300-member chamber - 80% of whom would be elected for single 15-year terms.
Clegg said that it was a fundamental principle that the people who make the laws should be elected rather than being chosen by the "clammy hands" of party leaders such as himself as is currently the case.
"What kind of politicians do people prefer? People who are placed in the House of Lords through patronage, or politicians who are placed in the House of Lords through election?" he said.
The Lib Dem leader also told the assembled peers and MPs that he was troubled by the suggestion that the chamber would be "dumbed down" if elected peers were let in - noting that there were several experts sitting in the House of Commons.
He also said current Lords debates were often characterised by "out-of-date" opinions.
"I am really unsettled by this idea that there is this pristine, uncluttered expertise in the current House," he said. "Don't over-romanticise the House of Lords as it is today."
However many MPs and peers are concerned that an elected upper chamber would challenge the primacy of the House of Commons leading to legislative gridlock and even forcing the Supreme Court to intervene.
Mark Harper, the Conservative minister for constitutional reform who was appearing alongside Clegg, said the primacy of the Commons would be maintained as the Parliament Act would always give it the power to overrule the Lords.
And he noted that the government would be formed based on which political party had a majority in the Commons - providing it with significant power.
But Lord Trimble, the former leader of the Ulster Unionist Party said he was worried that once elected, new members would be unaccountable and therefore have no check on their power.
"The great power of the electorate is they can turn people out. With this new elected House the electorate will never be able to turn it out," he said.
"It is literally irresponsible. Something that is literally irresponsible is liable to behave in an irresponsible way."
He said an elected second chamber would have "greater legitimacy" because it had been elected but would be "free to do whatever it likes" because it would not have to stand for re-election. This would create a "dangerous machine at the heart of government" he warned.
But this was rejected by Harper, who said he had not observed MPs, who had decided not to stand for re-election to the Commons, "suddenly going mad and running around being irresponsible".
Clegg and Harper's appearance at the committee came amid signs of tensions between some Conservative and Lib Dems on the issue of Lords reform.
On Sunday Lib Dem peer Lord Oakeshott suggested his party may block the proposed changes to constituency boundaries, desired by the Conservatives, unless they supported reform of the House of Lords.
"If you go back on the deal on that I can assure you, you won't find Lib Dems in parliament at all keen to vote for redistribution," he told Tory MP Philip Davies.
When Davies indicated he would vote against Lords reform, Lord Oakeshott replied: "Okay, well in that case you'll be fighting the next election on the old boundaries, Philip."