David Cameron and Nick Clegg will stage a show of coalition unity tomorrow 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 re-draw 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.
"These differences matter and at the next election they will help define us. But we're not in an election, now. We're not even close," he said.
"People see riots and financial instability across Europe on the television news. They will tolerate tough choices if they see that you stand up for the right things together.
"But they will not tolerate division and navel-gazing. They know that the problems are big and they do not want to see politicians fall out in the process of dealing with them.
"That is why we must rise to the challenge, recognise the extraordinary and challenging nature of the times we live in - and serve the national interest by delivering a strong, decisive and united government."
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.
Tomorrow's 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.
Among the projects expected to benefit are:
:: Electrification - completion of the Midland Main Line from Bedford to Sheffield, local lines in the Welsh Valleys, and an extension of the already-announced electrification between Manchester and Leeds;
:: The Northern Hub: A series of projects around Manchester that improve northern rail capacity so as to get more and faster trains across the north of England;
:: Upgrades to the East Coast Line from London to Leeds and Newcastle;
:: The reopening of the east-west link from Oxford and Aylesbury to Milton Keynes in Buckinghamshire;
:: Electrification of the lines from London to Bristol and Cardiff, and from Manchester to Liverpool, Blackpool and Leeds.
Shadow transport secretary Maria Eagle said the investment would only come through after the next general election in 2015.
"It is rail investment now, not post-dated cheques, that will deliver jobs and growth," she said.
"The Tory-led Government cut the rail investment plans they inherited by more than three-quarters of a billion pounds and have presided over two years of dither and delay over vital rail projects and train procurement.
"Setting out plans for way beyond the next election helps the industry to plan ahead, but does nothing to boost the economy now."