Britain’s opposition Labour Party has committed to keeping for at least five years the so-called triple lock that guarantees rises to state pensions, if it wins the election, underscoring the importance of pensioners to the outcome of the vote.

Labour have held an around 20-point lead in opinion polls over Prime Minister Rishi Sunak’s Conservative Party for the last nine months, but the one area where they tend to struggle is with voters over 65 years old.

Labour leader Keir Starmer told the Daily Express newspaper that pensioners needed certainty, and he would commit to retain the policy of increasing publicly funded pensions by the level of earnings, inflation or 2.5%, whichever is highest.

“That’s why I’m guaranteeing the pensions triple lock will be in the Labour manifesto and protected for the duration of the next parliament,” he said on Sunday.

The policy was introduced by a Conservative government in 2011 to prevent pensioners from falling into poverty.

But the cost of the commitment has come under increased scrutiny in recent years after British inflation soared, pushing up the government bill for state pensions by an additional 11 billion pounds ($13.7 billion) last year.

Sunak’s government has also committed to retaining the policy.

The Labour commitment is just the latest policy from either party as the country edges towards an election that is due by Jan. 28 next year. Most political analysts expect Sunak to call the election for October or November, giving more time for inflation to fall and the economy to grow, but he has not given a definite date.

Sunak, in an interview with Sky News broadcast on Sunday, declined to rule out holding the election in July, when he was asked about his previous comment that it would likely be held in the second half of the year.