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Senior Labour figures are considering the option of forming a minority coalition with the Liberal Democrats, the BBC has learned.

The move is to counter claims a Labour government would lack legitimacy if it won fewer seats than the Conservatives.

Senior Labour sources say such a coalition would have collectively more seats than the Conservatives.

They hope this might give an Ed Miliband-led administration greater legitimacy in the eyes of voters.

Labour could form the next government even if it has fewer MPs than the Tories and both parties have no majority.

Legitimacy questions

What matters constitutionally is not which party comes first or second, but which can command the confidence of the House of Commons with the support of other parties.

Some Tory ministers have begun to argue that it would be illegitimate for Labour to form a government if it "came second" behind the Conservatives - in an attempt to shape the agenda for the day after the election if no party wins outright, the Tories win most seats and David Cameron tries to stay on in Downing Street.

But Labour sources say that a coalition with the Lib Dems would not only give an Ed Miliband minority government greater legitimacy, it would also give it greater stability.

They say that while coalition would not give Labour a majority in the House of Commons, it would give the government the ability to out-vote the Conservatives regularly whenever the SNP abstain.

They also say that coalition with the Lib Dems would make it much easier for a Labour-led government to get its business through the House of Lords where no party has a majority and where 102 Lib Dem peers are a key swing vote.

The inability to overturn defeats in the House of Lords has been one of the biggest difficulties faced by minority governments in the past.

'Coalition of losers'

There would be many hurdles to be overcome before any Labour-Lib Dem minority government could be formed.

It would be accused by opponents of being a "coalition of the losers".

Many Lib Dems would be opposed to minority coalition: not only would the party have to compromise yet again on its policies in return for power, but it would also have even less chance of getting its own policies implemented.

A Labour spokesman said: "This is post-election speculation. Every hour until polls close we are going to spend on winning a Labour majority.

"We are focused only on winning a Labour majority."

A Lib Dem spokesman said: "If there is a hung parliament we will do what we did last time: seek to work in the national interest to provide stable government and deliver the policies we believe will help to build a stronger economy and a fairer society.

"As last time, it is right that the party with the biggest mandate from the British people - the most votes and the most seats - should be given the first opportunity to reach out to other parties.

"It is clear that no party will win the election outright.

"Voting for Liberal Democrat MPs will keep Britain on track and not allow the Tories or Labour lurch off to the extremes of left or right."

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