William Hague has upped the political ante and called for Tony Blair to scrap plans for a May 3 general election.

Hague on Thursday demanded that the prime minister "put country before party" and shelve plans for an election next month in order to focus on the continued foot and mouth crisis.

The call came as a MORI poll shows that the crisis in the countryside has failed to dent Labour's huge poll lead.

The Tory leader used a visit to Cumbria, an area devastated by foot and mouth disease, to call on the prime minister to postpone the local and general elections.

He said "we have a national epidemic that is out of control," arguing he would not call an election in these circumstances.

Hague's call comes as the number of foot and mouth cases jumped yesterday to 729, the highest increase to date.

Whilst Hague has in recent weeks told the prime minister that he should make contingency plans to delay the election, this is the first time he has called for a May 3 election to be abandoned.

All the signs are that the prime minister will stick to his guns, taking his final decision on Monday. Some Labour sources suggest that the favoured alternative of June 7 is gaining ground although the majority still want and expect a May 3 election.

Private Labour polling shows the party on 44 per cent - 16 points ahead of the Tories - and is backed up by a MORI poll in Thursday's Times putting Labour at 50 per cent and the Conservatives 31 per cent (with the Lib Dems on 14 per cent).

The poll shows that the new Conservative strategy is high-risk. Hague faces an uphill task with the polls indicating that Labour's popularity remains immune to foot and mouth and increasing economic pessimism.

In spite of high levels of public dissatisfaction - 66 per cent - with government efforts to combat the foot and mouth epidemic, Blair is still enjoying a significant poll leads over Tories.

The figures also indicate that Hague's accusation that Labour is putting "party before country" may be of limited appeal.

Labour's support is growing in urban areas and slipping in the countryside - a shift that operates in inverse proportion to Conservative popularity.

The Tories are down one point in urban areas to 28 per cent where Labour is up three points to 55 per cent.

In the countryside, the Conservatives are up nine points to 35 per cent and Labour is down three points to 41 per cent.

But Labour will have to watch its "heartlands" with MORI showing that only 72 per cent of its supporters are prepared to vote - compared to 81 per cent of Tories.

The differential turnout is unlikely to upset the party balance but shows that Labour's greatest electoral battle lies in convincing its own people in predominantly urban areas to vote when the election does finally come.