Tensions in the coalition came to the fore today as a Lib Dem peer warned the party might block boundary change proposals unless the Tories supported reform of the House of Lords.
Lord Oakeshott's comments came as Conservative MP Philip Davies revealed he would vote against Lords reform.
The Lib Dem peer told BBC One's Sunday Politics chaired by Andrew Neil that he believed it was time to move to wholly or mainly an elected second chamber and the principle of hereditary peers was "undemocratic".
Davies maintained that the House of Lords "works", adding it was "amazing that the Lib Dems want to change a chamber that's actually largely proportionate".
The Tory MP sought to draw a contrast with the European Commission, which he said was "totally unelected and unaccountable" but backed by the Lib Dems.
Lord Oakeshott stressed the coalition agreement stated a committee would be established to bring forward proposals for a wholly or mainly elected second chamber on the basis of proportional representation.
He said: "And 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, you know. If you want a fight...."
Outlining his views on the House of Lords, the MP for Shipley said: "Why on earth we'd want to turn the House of Lords which has all that expertise and experience into a poor man's House of Commons is absolutely beyond me."
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."
Asked by Neil if the Tories did not deliver on Lords reform, whether the Lib Dems would oppose the boundary changes, Lord Oakeshott said:
"I think we will not be wanting to put that through if they welch on the other half of the deal - no, a deal's a deal."
He added: "I think if Philip and his friends persist in these wrecking tactics and not sticking to the coalition agreement it's going to make it very difficult."