More than four million viewers tuned into BBC One’s televised election debate, more than two million shy of a previous debate on ITV.
An average audience of 4.3 million watched the event, featuring leaders of five opposition parties, but not the Conservatives and Liberal Democrats.
It represented a 20.5% share of Thursday evening’s total audience.
On 2 April, an average audience of seven million tuned in to ITV to watch the seven key party leaders debate.
That debate, which included David Cameron and Nick Clegg, gave ITV a 31.2% share of the total audience.
The BBC’s debate, which took place at the Methodist Central hall in Westminster, included the leaders of Labour, Plaid Cymru, the Green party, the SNP and UKIP.
It ran for an hour and a half from 20:00 until 21:30 BST.
Hosted by David Dimbleby, the debate clashed with ITV soap Emmerdale at 20:00, which drew an audience of 5.2 million.
A follow-up programme – from 21:30-22:00 – featuring reaction to the debate saw the average audience dip to 3.5 million and a 17% share.
A snap poll taken immediately after the debate suggested Labour leader Ed Miliband had come out on top.
The debate also saw some controversy when UKIP leader Nigel Farage criticised the studio audience which he described as “left-wing” and “hostile” to his party.
The BBC said the audience had been selected by an independent polling company to represent the spread of opinion in the population.
The BBC is to host a special Question Time on 30 April, again presented by Dimbleby, which will feature Cameron, Clegg and Miliband.
The general election will be held on 7 May.