David Cameron will attempt to reclaim the "One Nation" slogan from Labour when he promises to make the NHS the world's first seven-day-a-week health service.
The prime minister will make the commitment in his first major speech after the Tories secured a shock majority in the House of Commons at the general election.
Cameron, who is expected to speak at a GP surgery in the West Midlands, will also renew his pledge to fund the NHS by £8bn ($12bn) per year by 2020 in a bid to fill the service's £30bn a year funding gap.
"There is nothing that embodies the spirit of One Nation coming together – nothing that working people depend on more – than the NHS. Our commitment to free healthcare for everyone – wherever you are and whenever you need it," the prime minister will say.
"That means getting the best care and making that care available for everyone – free – wherever they are and whenever they need it.
"So I believe that together – by sticking to the plan – we can become the first country in the world to deliver a truly seven-day NHS. We must do so to protect and preserve the values of the NHS that are so central to our national identity."
Labour, who used Benjamin Disraeli's "One Nation" motto in the run-up to the election, warned that Cameron has not outlined how he will pay for the NHS reforms.
Andy Burnham, the shadow health secretary, said in March: "Not only has [Cameron] failed to deliver on that promise, he made it harder for people to get a GP appointment from Monday to Friday. It is typical of the brass neck of a man who thinks he can take the public for mugs.
"With the NHS in increasing financial distress, Cameron must set out clearly how it will be paid for. His extreme plans for spending cuts will mean they won't be able to protect the NHS."