The Rotherham by-election was "disastrous" for the Liberal Democrats, Vince Cable has admitted.
The Business Secretary said last Thursday's eighth-place result showed there was a lot of "disillusionment" among voters which led people to protest and switch support to Ukip, which came second behind Labour, and other smaller parties such as Respect and the BNP.
Analysis of the past six Westminster by-elections shows that the Lib Dem share of the vote has dropped from 18.9 per cent to 6.8 per cent.
Mr Cable told Radio 4's Any Questions? that the Rotherham social services adoption row, where children were removed from Ukip-supporting foster parents, helped the anti-EU party. But he added: "The [Rotherham] by-election itself, let's be frank, was disastrous for both of the coalition parties and particularly for mine.
"But there is a lot of disillusionment, and I can understand why people protest."