MPs are to vote on controversial government plans to put a 1% cap on annual rises in working-age benefits and some tax credits until 2016.
Benefits have historically risen in line with the rate of inflation, and increased by more than 5% in 2012-3.
Labour, which opposes the cap, says it will result in a real-terms cut in support for millions of working people.
The coalition says public sector pay is capped at 1% and benefits should not be rising at a faster rate than wages.
Work and Pensions Secretary Iain Duncan Smith said inaction would leave the UK "bankrupt", and that "like Greece and like Spain... we'll have huge borrowing costs".
He told BBC Radio 4's Today programme the last Labour government had created an "outrageously messy system", which had to be reformed.
I support the cap, and hope that the coalition win the vote.
http://www.bbc.co.uk/news/uk-politics-20936833