A grim year for the Liberal Democrats – during which they were trounced in by-elections and slumped to single figures in the opinion polls – has been capped by a spectacular fall in donations.

Nick Clegg’s party was given £2,481,707 in gifts during 2012, a drop of more than 40 per cent from the £4,161,018 it received the previous year.

The slide was disclosed by the Electoral Commission, which reported that donations to the other two main parties held up well over the period.

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The drop in funding will intensify the growing financial pressure on the Liberal Democrats since they went into Coalition with the Conservatives. They are mounting an expensive by-election campaign in Eastleigh involving hundreds of activists and intensive leafleting and phone canvassing.

The party has a less reliable stream of income than its rivals. The Tories can count on large donations from rich individuals and companies, and Labour on trade union support.

A spokesman said: “Compared with the last parliament, we are raising more money from more people than ever before.” He said smaller donations not recorded by the Electoral Commission were also rising.

The Tories took £13,801,282 last year, slightly down on their total of £14,230,027 in 2011.

Labour donations crept up marginally from £11,963,093 to £12,036,055 last year.