The Labour Party will pledge to keep the state pension triple-lock until 2025, in an announcement tomorrow.
Speaking at an arts and crafts exhibition, shadow chancellor John McDonnell will outline a series of policies aimed at pensioners.
The Conservatives have promised to keep the triple-lock, which guarantees pensions rise in line with average earnings, inflation, or at a rate of 2.5 per cent, until at least 2020. The party has so far avoided to committing to it beyond then.
In November, the work and pensions committee said that the triple-lock should be scrapped because it was "unfair" on younger families.
Steve Webb, former pensions minister and current director of policy at Royal London, said it is difficult to assess how much it will cost to maintain the triple-lock on pensions for such a long period of time.
"It’s an uncosted commitment, which is always worrying," he said.
McDonnell will say tomorrow: "I am delighted to be launching this pledge card that will inform many elderly people in our communities that Labour is not only promising to stand up for pensioners; but is determined to ensure they keep the hard-won entitlements they currently hold.
"It's a national scandal that pensioner poverty is rising."
Labour has also promised to keep the winter fuel allowance and free bus passes for pensioners.