Ed Miliband has promised that a Labour Party government will recruit 36,000 NHS doctors, nurses and midwives by 2020 if it gains power at the 2015 General Election.
Miliband, speaking to at the Labour Party's annual conference in Manchester, said the recruitment drive will be paid for by a new "mansion tax" on homes worth more than £2m ($3.2m, €2.5m) and levies on tobacco firms.
The party leader also said that a Labour government will clamp down on tax avoidance to raise more than £1bn.
These policies will create a £2.5bn "time to care" fund to boost the NHS and create 20,000 more nurses, 8,000 more GPs, 5,000 more care-workers and 3,000 more midwives, according to Miliband.
He also warned that the NHS was not safe for another five years under David Cameron's stewardship and promised that Labour will "transform the NHS for the future".
"That is what the next Labour government will do and we will do it together," Miliband said.
The pledge is one of Miliband's "six goals", which make up the Labour Party leader's plan to govern Britain over the next ten years.
"For Labour, this election is about you," Miliband said.
"You have made the sacrifices, you have taken home lower wages year after year, you have paid higher taxes, you have seen your energy bills rise, you have seen your NHS decline, you know this country doesn't work for you."
The announcement comes less than eight months until the 2015 General Election.
The latest opinion poll from YouGov for The Sun newspaper, which questioned 1,671 people, found that 33% of respondents would vote for the Conservative Party at the next election, against 35% of people who would vote for Labour.