David Cameron and Nick Clegg are due to stage a show of coalition unity as they unveil plans for the biggest investment programme in the railways since the Victorian era.
The Prime Minister and his deputy will announce a £9 billion injection into the network as they seek to draw a line under the latest bout of sniping between their two parties.
Over the weekend Mr Cameron urged Conservatives and Liberal Democrats to come together behind the coalition and not to descend into "division and navel-gazing".
However, his appeal failed to halt the angry exchanges in the wake of last week's Tory revolt which threatens to derail Mr Clegg's plans for House of Lords reform. Former Lib Dem leader Sir Menzies Campbell warned that his party's MPs may refuse to back Conservative plans to redraw parliamentary boundaries - thought to be worth an extra 20 seats to the Tories at the next general election - unless Lords reform goes ahead.
"If you are a Liberal Democrat MP whose seat has been pretty substantially carved up as a result of the proposals for a review of the boundaries, then the idea that you would simply march into the lobby in support of the Conservative Government's particular anxiety to obtain this piece of legislation is one that may be very hard to swallow," he said.
On the Conservative side, former defence secretary Liam Fox said the Tories needed to be more assertive with their Lib Dem coalition partners. "We have a particular problem which is the Liberal Democrats," he told The Sunday Telegraph. "What I think they have to remember is that they are a sixth of the coalition, not half the coalition."
Writing in The Sunday Times, Mr Cameron frankly acknowledged there were "profound areas of disagreement" between the two parties but said it was essential that did not stop them working together in the national interest. Mr Cameron did offer an olive branch to Conservatives who feel that he has given too much ground to the Lib Dems - spelling out some of the areas where they will campaign on different policies at the next election, including the EU, the European Convention on Human Rights and welfare reform.
The announcement on rail investment covers the period 2014 to 2019 and is expected to include £5 billion for the completion of on-going projects such as Thameslink and the cross-London Crossrail and £4.2 billion for new schemes.
Later, the chairman of the Tory backbench 1922 Committee, Graham Brady, said he believed the coalition was "very likely" to end before the general election, set for 2015.
"I think it would be logical and sensible for both parties to be able to present their separate vision to the public in time for the public to form a clear view before the election," he told BBC Radio 4's The Westminster Hour. "Of course, it is always possible that that moment of separation could come sooner. It's very difficult to predict when that might be."