By William James
LONDON (Reuters) - The leader of Britain's opposition Labour Party, Ed Miliband, faced fresh pressure on Sunday as a poll showed backing for his leadership among party supporters had fallen sharply, days after he was forced to dismiss rumors of a plot to oust him.
A YouGov poll found that the number of Labour voters who believed Miliband was fit to be prime minister had fallen to 34 percent, down from 51 percent in October. Forty two percent said they thought he was unsuitable for the job, up from 28 percent in October.
Despite Labour holding a narrow opinion poll lead six months before a parliamentary election, Miliband's personal ratings are at an all-time low amid criticism of his image and his handling of key electoral topics such as immigration and the economy.
"His biggest task is to persuade people he has the gravitas to be prime minister, I think this is his biggest personal failing in terms of the public," YouGov President Peter Kellner told the BBC.
The YouGov poll, published in the Sunday Times, asked just under 500 people who had voted for Labour in 2010 whether they thought Miliband was up to the job of prime minister. The full results of the poll, which surveyed 2,022 people, put Labour on 33 percent overall, level with Prime Minister David Cameron's Conservatives.
Miliband's future dominated the front pages of Britain's Sunday newspapers with the Observer reporting that 20 unnamed members of his team wanted a change of leader.
On Thursday, after similar reports of Labour members of parliament plotting to depose him, Miliband said speculation about his leadership was "nonsense", and on Friday the party's campaign co-ordinator urged the party to unite or risk losing the election.
Miliband's former chief of staff, Lucy Powell, criticized the anonymous lawmakers calling for his head.
"What I would say to those people is 'be careful what you wish for'", she told BBC radio. She called the anonymous briefing "cowardly", and said it risked distracting the party from its election campaign.
(Editing by Aidan Martindale)