The Tory leader is in Wales as the party prepares to launch its Welsh manifesto for the general election.
Mr Cameron has made Labour's record in office in Cardiff Bay a big part of the general election campaign, with references to the NHS's performance.
"The dragon on our flag may be red, but our country will always be better off blue," he will say.
"The people of Wales already know more than most the damage Labour can do.
"Cutting health spending and taking their eye off the ball on education.
"This is the way Labour treats the nation of Nye Bevan and Dylan Thomas.
"Seriously, where is it written that Wales votes Labour?"
Mr Cameron will say that jobs and the economy are the issues that matter most to voters at the election.
And he will use the growing aerospace industry as an example of Wales's economic success over the past few years.
In the next parliament, the Conservatives are pledging to increase the tax free personal allowance to Â£12,500, benefitting 1.4m tax payers.
Secretary of State for Wales Stephen Crabb said this shows a Tory government will "get things done for Wales."
There is also a commitment to make people working 30 hours on the minimum wage exempt from paying income tax.
As part of the launch, the Tories will highlight their record in Wales during the last five years of government.
This includes 52,000 new jobs and 22,400 businesses created since 2010, as well as 1.2m people getting a tax cut.
Welsh Conservatives have also said that the Â£8bn extra pledged to fund the NHS in England will result in more money for the Welsh government.
Mr Crabb said: "By rolling up our sleeves and facing Wales' challenges head on, our ambitious programme for the next five years will create new and better jobs for Wales."
UKIP will also launch its Welsh manifesto on Friday.
People in Wales know "more than most the damage Labour can do", David Cameron will say today.