Cameron's address on Wednesday promised tax cuts for 30 million workers if the Conservatives win the May 2015 general election and his speech was largely seen as a pitch to be returned to office.
The poll put the centre-right Conservatives on 35 percent, with the opposition centre-left Labour Party, led by Ed Miliband, on 34 percent.
The populist United Kingdom Independence Party (UKIP) was on 14 percent and the centrist Liberal Democrats, the junior partner in the coalition government, on six percent.
The survey found people expect their finances to suffer less under a Conservative government, but believe they will be poorer in five years' time irrespective of who wins.
YouGov president Peter Kellner said the big polling issues ahead of the election remained unresolved.
"Can the Tories turn their big lead over Labour on the economy into extra votes as the election approaches? Can Miliband persuade floating voters that he is up to the job of prime minister?" he asked.
YouGov surveyed 2,133 British adults on Wednesday and Thursday.
