Nick Clegg has told MPs it is "reasonable" to cap the amount of housing benefit claimants can receive.
Shadow constitutional reform minister Chris Bryant said at deputy prime minister's questions that the government's "niggardly" proposals would see 200,000 people "cleansed" from the centre of London.
He claimed the capital would become like Paris with the poor only able to live on the outskirts of the city. He also suggested poor people would be disenfranchised by his proposals.
Clegg accused Bryant of hyperbole and said his use of phrases like "cleansing" was "deeply offensive" and "outrageous".
The deputy prime minister said it is reasonable for the government to say no-one should be handed more in benefits than an average family earns.
Henry Smith (Con, Crawley)asked for an update on plans for an elected second chamber.
Mark Harper, parliamentary secretary to the cabinet office, said there will be a draft bill next year and a joint committee of both Houses will consider the options.
Smith said it was right that those who make laws are elected.
Nigel Dodds (DUP, Belfast North) questioned why the government wants a cross-party approach on this issue but is "rushing through other changes".
Harper said the Parliamentary Voting System and Constituencies Bill has had five days of debate on the floor of the House and there will be two more days next week.
Duncan Hames (Lib Dem, Chippenham) said the public has been waiting 100 years to elect the Lords and asked when they would finally get the chance.
Harper said that will be a matter for the committee.
Sadiq Khan, who shadows the deputy prime minister, said Labour will support constitutional reform "if done for the right reasons".
He claimed the bill before Parliament will remove 50 elected representatives, most of them Labour, while the coalition is appointing 50 more unelected peers.
Harper said Gordon Brown created 29 new Labour peers in his resignation honours and the government has no plans to pack the upper House.
Julian Lewis (Con, New Forest East) warned against turning the Lords into a carbon copy of the Commons.
Harper said that would not be "sensible" and the committee will consider how to avoid that.
Asked about lowering the voting age, Clegg said he has "no current plans to do so".
Willie Bain (Lab, Glasgow NE) said 16 and 17 year olds contribute £500m in tax and 4,500 of them are serving in the armed forces and they should be allowed to vote.
Clegg said he personally supports votes at 16 but he is open about the disagreements within the coalition about the issue.
Gary Streeter (Con, SW Devon) said that in the last three general elections less than one third of 18 to 25 year olds voted and called votes at 16 a "ridiculous proposition".
Clegg replied that being entitled to vote should not depend on whether one exercised that right.
Andrew Stephenson (Con, Pendle) said he welcomed plans for individual voter registration but called for more restrictions on who can use postal votes as they are open to abuse.
The deputy prime minister said any incidence of voter fraud is unacceptable.
Harriet Harman, shadow international development secretary, asked Clegg if he takes responsibility for the 500,000 private sector jobs that she claimed will be lost because of the cuts in public spending.
Clegg said according to the Office of Budget Responsibility there will be two million more private sector jobs by the end of this spending period.
He added that even after 490,000 job losses in the public sector, there will be 200,000 more jobs in that sector than there were in 1997.
Harman said the government is punishing people who are trying to find work by cutting their housing benefit. She asked him to review the policy.
Clegg said increasing incentives to work is "the centrepiece of government policy" along with measures to lift people out of income tax and welfare reform.
James LeFroy (Con, Stafford) praised the announcement that the UK will triple its annual spending on fighting malaria to £500m a year until 2014.
The deputy prime minister said it was an example of the country's commitment to the poor across the world and the extra money will cut malaria deaths by 50 per cent in "high burden countries".
John Cryer (Lab, Leyton and Wanstead) condemned plans to cap housing benefit.
Clegg said housing benefit rose from £10bn to £21bn in the last decade.
Stephen Mosley (Con, City of Chester) called for reform of trade union funding.
The deputy prime minister said Labour leader Ed Miliband was only elected thanks to the duplicate votes of trade unionists.
He urged co-operation and compromise with the unions rather than "pitching the country into confrontation".
Ian Mearns (Lab, Gateshead) said smoking reduces the life expectancy of many of his constituents. He condemned Clegg for "promoting" smoking during his recent appearance of Desert Island Discs.
The deputy prime minister replied that he was not seeking to promote smoking which is "a very bad habit".
Clegg was also asked about the plans for a committee to examine the West Lothian question; the increase in social housing rents; allegations of voter fraud in Tower Hamlets and the problems of being an MP and trying to raise small children.
Anas Sarwar (Lab, Glasgow Central) asked the deputy prime minister to apologise to "the students be betrayed since he became a Tory" and abandoned his pledge on tuition fees.
Clegg said he regrets making a pledge he is unable to keep, while a graduate tax is neither workable or fair.