Tories increase lead to 19 per cent as Labour suffer in wake of Budget

But huge majority want Cameron to explain what he would do for the economy as PM

The Conservative Party has stretched its lead over Labour from 12 to 19 points following last week's Budget, according to the latest monthly opinion poll for The Independent.

And in a further blow to Gordon Brown, former Cabinet minister Stephen Byers last night launched a stinging attack on the new 50p tax rate for the highest earners, saying it had been introduced for "cynical political reasons" and in the long term would damage both Labour and the economy.

The ComRes survey puts the Tories on 45 per cent (up five points on last month), Labour on 26 per cent (down two points), the Liberal Democrats on 17 per cent (down one point) and other parties 12 per cent (down two points). If repeated at a general election, the figures would give David Cameron an overall majority of 186. However, the findings suggest that the Tories' advance may be based mainly on an anti-Labour protest vote rather than positive support for Mr Cameron's party. Only 38 per cent of people believe the Tories have the right ideas about how to get Britain out of recession, while 49 per cent do not think so. Although 71 per cent of Tory supporters think the party has the right ideas, only about one in five Labour and Liberal Democrat supporters agrees.

A huge majority of people want to know more about Tory policies; by 79 to 14 per cent, they want Mr Cameron to be clearer about what he would do about the economy if he were prime minister. The view is not confined to people who do not intend to vote Tory; some 82 per cent of Tory supporters want to know more, as do 84 per cent of Labour supporters and 83 per cent of Liberal Democrat supporters.

The Tories' general approach to the economic crisis is more popular than Labour's. By a margin of 55 per cent to 38 per cent, people believe the shortfall in the public finances should be met by cuts in public spending rather than tax rises. Seven out of 10 Tory supporters prefer spending cuts to tax rises, but the figure drops to 46 per cent of Labour supporters and 42 per cent of Liberal Democrat supporters.

By 55 to 35 per cent, people say they do not trust Gordon Brown more than Mr Cameron to lead Britain out of recession. The PM is trusted by three in four Labour supporters to steer the economy to recovery but by only 18 per cent of Tory supporters and 26 per cent of Liberal Democrat supporters.

According to ComRes, the Tories are now ahead of Labour in every age group and social class and in every region of Britain except Scotland. Some 94 per cent of people who voted Tory in the 2005 general election say they would support the party again now. For Labour the figure is 62 per cent and for the Liberal Democrats 68 per cent.

Significantly, Mr Cameron is broadening his party's appeal. One in five (21 per cent) of people who backed Labour in 2005 and 24 per cent of those who voted Liberal Democrat have now switched to Mr Cameron's party – up from 12 per cent and 16 per cent in March respectively.

Some 63 per cent of those who regard themselves as natural Tories say they are "absolutely certain" to vote at the next election, compared to 48 per cent of Labour identifiers and 51 per cent of natural Liberal Democrats.

Yesterday, Mr Cameron challenged Mr Brown to call a referendum on the European Union's proposed Lisbon Treaty. "The Lisbon Treaty is hugely significant," he said. "It is, by all accounts, a constitution. That is why we are making this such an important issue at these European elections [on 4 June]."

ComRes telephoned 1,003 adults between 24 and 26 April. Data were weighted by past vote recall. ComRes is a member of the British Polling Council and abides by its rules. Full tables at www.comres.co.uk