Party leaders are criss-crossing the country in a frenetic final round of campaigning ahead of Thursday’s polling.
However, Nick Clegg has warned that voters could be forced back to the polls before Christmas.
The Liberal Democrat leader warned that only a coalition involving his party could provide “stable” government after tomorrow’s vote.
He claimed that any attempt by the Conservatives or Labour to run a minority administration with the support of parties such as Ukip or the Scottish National Party would be “a shambles”, and predicted it would force voters back to the polls before the end of the year.
The Deputy Prime Minister’s words came as David Cameron appeared to indicate that he was ready to seek a new coalition in the case of a hung parliament.
He told a member of the public that he would “always put the country first”.
Meanwhile, shadow health secretary Andy Burnham said that Labour would do whatever it can to put its agenda before Parliament in a Queen’s Speech.
This prompted Tory claims that Ed Miliband’s party would attempt to form a government even if it meant being propped up by the Scottish National Party.
In an apparent signal that he was open to a fresh coalition with Tories, Mr Clegg said that avoiding an in/out referendum on Britain’s EU membership would not be a “red line” deal-breaker for Liberal Democrats in any coalition deals.
While both of the biggest parties insisted they were fighting for an absolute majority, the latest slew of polls continued to point towards a neck- and-neck finish and a hung parliament.
A daily YouGov poll for the Sun had the Conservatives and Labour on 33%, Ukip on 12%, the Liberal Democrats on 10% and the Greens at 5%.
A separate Populus survey showed the two main parties deadlocked on 34%, with Ukip on 13%, the Lib Dems on 10% and the Greens on 5%.
Visiting Cardiff during a 1,000-mile two-day battle-bus odyssey from Land’s End to John o’ Groats, Mr Clegg said: “Everybody knows that no one will win this election even if David Cameron and Ed Miliband won’t admit it publicly.
“The Liberal Democrats have shown that coalitions can be strong and stable,” he said.
“But instead of creating stability, Labour and the Conservatives will create a shambles.
“The last thing Britain needs is a second election before Christmas.
“But that is exactly what will happen if Ed Miliband and David Cameron put their own political interest ahead of the national interest.”