Labour would restrict out-of-work benefits for young people to give larger handouts to the over-50s, Liam Byrne has said.
The shadow work and pensions secretary said Labour was planning to increase the number of years unemployed young people have to pay national insurance to qualify for contributory job seekers' allowance (JSA).
Anyone younger than 24 who has paid national insurance for two years is entitled to contributory job seekers' allowance of £56.80 a week. But Mr Byrne said Labour would extend the number of years necessary to qualify for the benefit in order to ensure the over-50s received a "premium service".
The party is under pressure to show its spending plans add up. Earlier shadow chancellor Ed Balls said Labour would increase the bank levy to raise an extra £800 million a year to increase free ch ildcare places for three and four-year-olds from 15 hours to 25 hours a week.
But Mr Byrne said there would not be any new money for extending JSA for the over-50s.
He said : "We have got to look at how we transform social security for those in their 50s.
"If you are in your 50s, you have been in work all your life. You will have paid in more than £100,000 of national insurance but if you fall out of work, you are going to be out of work longer than almost anyone else and you are at a bigger risk of becoming disabled than anyone else.
"And what is there for you? Frankly, bugger all. That is wrong. We have said that those who have worked the most, cared the most and served the most, when you get to your 50s there should be a more generous benefits system for you, because what does that mean?
"It means you don't have to take the first job when it comes along just to keep your head above water and will give you more latitude to find a job that is a better match for your skills."
He added: "There is no new money for this. What we are going to have to say is that some contributory benefits will become less open, like contributory job seekers' allowance which you can get if you have paid in for two years.
"We are saying, well if we want to do this great thing for the over-50s then you are going to have to pay in for a bit longer.
"What we are trying to do is recast the system if you like so that different groups with different needs get the support they need."
Mr Byrne told the Labour conference that if you want someone to "really screw" things up, then you send for Work and Pensions Secretary Iain Duncan Smith.
He said: " And, conference, that is why we need to fire him."
Turning to the Government's Universal Credit policy, which aims to create a single payment for benefits, Mr Byrne said Labour was establishing a "rescue committee".
Earlier this month, MPs were told the amount of taxpayers' money wasted on IT systems for the Universal Credit scheme could rise by tens of millions.
A National Audit Office report revealed some £34 million has already been written off, but MPs on the Commons spending watchdog were told that figure could rise to more than £140 million.
Mr Byrne said: "If this Government won't act to save it, then we will. The Tories' system - it may prove dead on arrival - so we need a better way.
"So, today we announce our Universal Credit rescue committee.
"And I'm grateful to Kieran Quinn, leader of Tameside, the first pathfinder, for his offer to drive our work."