The Conservatives have upped the ante in the key election battleground of the NHS with a pledge to invest at least £8 billion extra a year in the health service by 2020.
David Cameron said the additional funding will mean over-75s will be guaranteed same-day access to GPs and patients will be able to see doctors out of regular office hours.
The investment is part of Mr Cameron's commitment to provide a full range of NHS services seven days a week.
Both Labour and the Liberal Democrats have attacked the announcement as an "unfunded" spending commitment.
Mr Cameron said he would protect the "amazing" health service by funding in full the five-year reform plan put forward by NHS chief executive Simon Stevens after he called for help in filling a £30 billion finance gap by 2020.
Mr Stevens said around £22 billion could be met through internal savings but demanded an extra £8 billion from the government.
Up to now only the Liberal Democrats had committed to finding the extra money.
Mr Cameron did not spell out exactly where the extra money up to 2020 will come from and his political rivals have been quite to undermine the Tory pledge.
A Liberal Democrats spokesperson said: "The Tories want you to think that they will invest in the NHS, but their claims cannot be trusted because their commitments are unfunded. Their extreme spending plans would see them cut twice as fast next year as last year, putting the NHS at risk."
A Labour spokesperson said: "The Conservative ideological obsession with cutting the size of the state means they cannot afford this unfunded spending commitment."
Meanwhile, Labour has announced its pledge of one-to-one midwife care for women during childbirth in its health manifesto.