His party may have no chance of winning the coming election, but Liberal Democrat economics spokesman Vince Cable won the plaudits in Monday's first live debate between possible chancellors.

Labour Party Chancellor Alistair Darling went head to head with Conservative rival George Osborne and Cable in an hour-long televised programme called "Ask the Chancellor" that is a forerunner for live debates between party leaders, a first in British politics.

With an election expected on May 6, opinion polls are pointing to a hung parliament where no one party has a majority, leaving the possibility that the two big parties, Labour and the Conservatives, try to form a government with the LibDems.

All three main candidates for the post of Chancellor admitted that spending cuts to bring down the record budget deficit would be the deepest in more than 20 years but offered no new detail and fell back on well-rehearsed lines.

"I am not sure we got to the heart of the debate but it was quite watchable," said Philip Shaw, chief economist at Investec.

The youthful Osborne, 38, was the first to speak on the Channel 4 programme broadcast in a prime evening slot.

He said that people knew early action on the deficit was needed and repeated his pledge made earlier in the day to cut wasteful government spending to reverse a planned rise in payroll tax for most people.

Darling, who has been chancellor since 2007, hit back that premature action could tip the country back into recession following the worst financial crisis for decades.

Cable, a former economist with Shell who has raised his public profile dur ing the credit crisis, slammed Osborne for denouncing Labour efficiency savings as fiction and then using the same trick to fund his tax cut.

The country's first past-the-post parliamentary system means the centrist LibDems have no chance of coming out victorious in the election but commentators have said that the higher profile from the TV debates might help them to maintain a bloc of around 60 seats in the 650-member parliament.

Channel 4's own online poll said 36 percent thought Cable performed best, with the other two level on 32 percent.

Denouncing Labour for causing the crisis, Cable said the Conservatives now wanted another turn "to get their noses in the trough and reward their rich backers" to cheering from the studio audience.

"Overall it was a win for Cable -- he pretty much dominated the other two, which was not unexpected. In terms of choosing between Osborne and Darling, it's hard to say who came out best. They just got so overshadowed by the other guy," said David Lea, Western Europe analyst, Control Risks.

(Additional reporting by Peter Apps)