The Liberal Democrats have admitted they are on course to lose at least 20 MPs, but claim this could still be enough to put them back in power. Nick Clegg today continued his tour of 60 seats where the party is defending perilous majorities or hope to make gains, stopping off in Hampshire where the Lib Dems held Eastleigh after Chris Huhne was jailed. But behind the scenes, senior party sources admit their current total of 57 MPs will be slashed to 'in the thirties' after a catastrophic collapse in support. Nick Clegg today continued his tour of 60 seats where the party is defending perilous majorities or hope to make gains, stopping off in Eastleigh in Hampshire . Mr Clegg today admitted that his party was fighting 'tooth and nail' in fewer than a tenth of Westminster seats. Instead of battling to win seats across the country, the party has highly targeted strategy, effectively fighting 60 by-elections in constituencies where his candidates stand a chance. A party source said if the party had a group of MPs numbering 'in the 30s' it could potentially hold the balance of power after May 7 and be able to once again form part of a coalition government. The senior Lib Dem, closely involved in the party's election strategy, said the campaign's focus was increasingly on between 10 and 15 marginal seats - some held by the party and a few targets - with other constituencies either assessed as safe or effectively written off. Assessing the election outcome, the source said: 'Everything is so marginal, we need to get into the 30s and the other parties need to sort themselves out and we will see what the answer is. 'There are now basically two possible outcomes to this election - we can either get a minority government or a coalition with the Lib Dems in it.' Asked if a seat count in the 30s was realistic, the source said: 'Oh yes.' Pressed on whether that was a 'best case' scenario, the senior Lib Dem said: 'I would like to say 150, but I think in fairness you wouldn't believe me. 'There are lots of marginal seats. There's a marginal outcome in 40 seats for us and if we won every one of those marginal contests we would get to 40-odd.' Mr Clegg today admitted that his party was fighting 'tooth and nail' in fewer than a tenth of Westminster seats . Opinion polls by YouGov since 2010 show the dramatic collapse in the Lib Dem support,  to barely 8 per cent . The Lib Dems won 57 seats in the 2010 election but have been hit by a slump in popularity after forming the coalition government with the Conservatives. Mr Clegg travelled to Eastleigh, the scene of a 2013 by-election triumph, to spell out the intensity with which the party would fight in its target seats. The Lib Dems have built up a reputation as formidable campaigners in by-election contests, including in the Hampshire seat which they held following the resignation of disgraced former cabinet minister Chris Huhne, despite a Ukip surge. Mr Clegg and the party's election strategists have insisted the poor national opinion poll ratings, which have seen the party stuck around the 8 per cent mark, are not reflected in the data gathered by canvassers and internal polling. The Lib Dem leader told supporters: 'What we are going to do on May 7 isn't just, as the placards say, win here, we are going to win up and down the country. 'Because in effect what we are doing is running a campaign of not just one Eastleigh by-election but 60 Eastleigh by-elections - north, south, east, west, campaigning with exactly the same vigour that led to that famous victory.' He added: 'In the final week of this campaign two million voters will hear our message on Facebook, on YouTube and on social media. 'So we are fighting a campaign like we have never fought a campaign before. Sixty by-elections up and down the country.' Mr Clegg was all smiles at the Ageas Bowl cricket ground near Eastleigh, behind the scenes, senior party sources admit their current total of 57 MPs will be slashed to 'in the thirties' after a catastrophic collapse in support. The alternatives to a coalition involving the Lib Dems were a Labour-SNP alliance 'saddling our children with the dead weight of debts from this generation' or a 'hapless David Cameron administration dancing to the tune of Ukip, the DUP and - most chillingly and worryingly of all - his own MPs on the right wing of the Conservative Party'. In a rallying cry delivered at Hampshire County Cricket Club's Ageas Bowl stadium he said: 'If you don't want to run the risk of our country lurching to the right, lurching to the left, the only way to guarantee to keep our country on track is to vote Liberal Democrat. 'We will cut less than the Conservatives, we will borrow less than Labour. We have provided a heart to a government with the Conservatives, just as we would provide a brain to a government with the Labour Party on the economy.' He added: 'We will win again. We will campaign like no other party knows how to campaign again. We will serve our local community better than any other party does again. We will speak to more voters than any other party again.' Asked whether he was now even running a national campaign following his call for '60 Eastleighs', Mr Clegg said: 'I am saying that exactly the same zeal of that by-election is what we are applying in the 60-odd seats where we are fighting tooth and nail to get Liberal Democrats elected in this election.' A new survey by Lord Ashcroft had the Tories on 36 per cent, with Labour trailing on 30 per cent, Ukip on 11 per cent and the Lib Dems on 9 per cent . The Tories could be six points ahead of Labour, or three points behind, depending on which opinion poll to believe. The latest batch of surveys agree on only one thing: the result is probably too close to call. David Cameron's day will have been brightened by a six-point lead in a survey by Lord Ashcroft. The Tories are on 36 per cent, with Labour trailing on 30 per cent, Ukip on 11 per cent and the Lib Dems on 9 per cent. Another poll by ICM for the Guardian also gave Mr Cameron's party a lead, but of only three points lead on 35 per cent to 32 per cent for Labour. However, the Sun's YouGov poll had Labour in the lead on 34 per cent to the Tories' 33 per cent, indicating that the battle for No 10 remains agonisingly close for the party leaders. Labour enjoyed a three-point lead in a Populus poll, on 36 per cent (up one point) to the Conservatives' 33 per cent (up one). North of the border, a TNS poll found Scottish National Party support continuing to surge to 54 per cent, almost two-and-a-half times Labour's 22 per cent.
Party on course to lose a third of the 57 seats it won in 2010, sources say .
Clegg admits party is fighting 'tooth and nail' in a tenth of constituencies .
Aides think that even 30 seats could be enough to hold balance of power .