Brown facing a spring revolt as MP compares him to defeated Anthony Eden

Gordon Brown faces a revolt against his leadership if Labour loses ground to the Tories at next May's local elections, MPs warned last night.

After a month marred by scandals over party donors, missing data discs and the collapse of Northern Rock, No 10 is braced for a possible coup.

One rebellious Labour MP even compared Mr Brown to Anthony Eden, the Conservative Prime Minister of the Fifties who resigned after less than two years in the job without fighting a single General Election.

Another backbencher claimed at least two former Cabinet Ministers were squaring up for a leadership challenge.

In the polls, the Tories have taken their biggest lead over Labour for 15 years, with women voters in particular deserting Gordon Brown.

According to the YouGov poll of nearly 1,500 people, Labour trail by 13 points. The Tories are on 45 per cent, against 32 per cent for Labour and 14 per cent for the Liberal Democrats, compared with 41 per cent, 35 per cent and 13 per cent a month ago.

The poll also shows an unprecedented drop in Gordon Brown's personal ratings. At the height of the Brown "honeymoon" in August the prime minister had a net approval rating of +48 per cent, the difference between those saying he was doing a good job and those saying he was doing badly.

In October, when he was agonising over whether to call an early election, his approval rating was still a healthy +30 per cent. But it has dropped to -10 per cent last month and to -20 per cent this month.

The lowest point reached by Tony Blair was -34 per cent in April 2006, which was at the height of the cash for honours scandal.

On May 1, the Prime Minister will face his toughest test yet when voters go to the polls to elect 143 English councils, all 22 local authorities in Wales and the London Mayor.

David Cameron's Tories are hoping to make big gains and if Labour loses more than 100 council seats, Mr Brown can no longer assume his job is safe. The warning comes as Labour falls further behind the Conservatives with voters.

A new poll puts the Tories on 45 per cent, up four points on last month and 13 points ahead of Labour who are down three on 32 per cent.

Mr Brown's reputation also takes a battering, with his approval rating – the difference between those who say he is doing a good job and those who say he is doing badly – slumping to minus 26 per cent, down from minus ten last month.

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The voters' views are reflected in a Mail on Sunday straw poll of Labour MPs, which reveals growing discontent over Mr Brown's performance.

Dr Ian Gibson, Labour MP for Norwich North, said: "If we lose seats in the May elections, serious questions will be asked aboutthe party leadership.

"Labour MPs will start to worry about losing their seats at the next General Election. Several people, including one or two ex-Cabinet Ministers, would then consider their leadership options."

There are signs already that Mr Brown is gearing up for the local elections – Labour by-election supremo Tom Watson has been a regular visitor to party Victoria Street headquarters over the past fortnight.

Should Mr Brown be forced to quit following May's ballot, Labour MPs are likely to turn to an experienced "grey beard" candidate.

Justice Secretary Jack Straw, 61, and former Home Secretary Charles Clarke, 57, will be the early frontrunners.

Thurrock MP Andrew MacKinlay called for a major clear-out of the Cabinet. He said: "We need to re-energise the party. Half the Government at all levels needs to be new and fresh."

A former Cabinet Minister and long-time critic of Mr Brown said Mr Brown had made "a series of stupid mistakes" and lost support and respect from Labour MPs.

Another member, who declined to be named, said: "People are talking about Gordon as Labour's answer to Anthony Eden – a leader who may be gone before he has a chance to fight an Election."

Eden succeeded Churchill as Prime Minster in 1955 and quit in 1957 following the national humiliation of the Suez Crisis, citing ill health. He died in 1977.

• Mr Cameron wants an alliance of Tories, Liberal Democrats and Greens to force Mr Brown into decentralising power from Whitehall. The Tory leader said such an alliance could "achieve social and environmental progress" through "empowerment" of individuals and communities.