UK poll gives Brown's Labour lowest-ever rating

LONDON (Reuters) - Britain's ruling Labour Party fell to its lowest-ever poll rating in a survey published on Friday, a week after big losses in local elections cast doubt on the leadership of Prime Minister Gordon Brown.

The YouGov poll conducted earlier this week and published in the Sun tabloid put Labour on 23 percent with the opposition Conservative Party on a 49 percent -- enough for it to win a landslide if national elections were held now.

Labour's showing was the worst since opinion polls were first published in the 1930s.

Brown, whose popularity has plummeted since he took over from Tony Blair last June, does not have to call a national election until mid-2010.

The media and the opposition accused him of dithering when he contemplated calling a snap election last October, before finally deciding against it.

There are rumblings of discontent inside the Labour Party with members fearing for their seats, and critics accusing Brown of lack of leadership.

The latest opinion poll showed a serious reversal of fortunes from eight months ago, when Labour support stood at 43 percent and the Conservatives were on 32 percent.

The influential Economist magazine asked in a leading article if Brown was doomed, concluding not just yet.

Beset by an economic downturn caused by the global credit crunch, an internal rebellion over tax changes that penalize some on low incomes and a series of bureaucratic bungles, Brown faces further tests in the next few weeks.

A by-election in a Labour stronghold on May 22 will be seen a test of his leadership, as will a parliamentary vote on extending pre-charge detention for terrorist suspects.

Brown has promised measures to offset some of the effects of the tax changes and, during a bruising parliamentary encounter on Wednesday, pointed to his 10 years of success as finance minister under Blair.

A glimmer of consolation for Brown was that the YouGov poll showed Labour would fare even worse under Blair -- and any of the members of Brown's cabinet that are occasionally mentioned as potential leaders.

(Reporting by Jeremy Lovell; editing by Andrew Dobbie)