Labour and the Conservatives are neck and neck in the opinion polls with 101 days to go before the general election in May.
A survey from YouGov for The Sunday Times, which was conducted between the 22 and 23 of January and questioned 1,578 people, found that Ed Miliband's and David Cameron's parties were both on 32%.
The latest Populus poll, which was conducted between the 23 and 25 January, put Labour just one point ahead of the Tories (35% vs 34%).
The data comes ahead of Cameron's speech the Conservatives' approach to tax policy.
The Tory leader is expected to argue that the public should get tax cuts after the election as a reward following the financial crisis of 2008 and subsequent recession.
"We're at that moment now – what I would call the tax moment, when after years of sacrifice, the British people deserve a reward," he will say.
"Let me put it like this: in the wake of Labour's Great Recession, these past few years have incredibly hard for this country.
"But after some dark times, we are coming out the other side. And as we do, I'm clear – the people whose hard work and personal sacrifices have got us through these difficult times should come first.
"So it's right that where we can ensure people keep more of their own hard-earned money, we should."
The announcement will be the third in a series of speeches from Cameron as he outlines his party's six election priorities, including the deficit, jobs, taxes, education, housing and retirement, ahead of polling day.