Prime Minister Theresa May has refused to say whether the Conservative manifesto will keep the "triple lock" on pensions which guarantees big increases in payments every year.
May pledged to raise the state pension during every year of the next Parliament if she is elected, but she said the pace of increases will be revealed in the manifesto.
When asked if she will drop the triple lock in an interview with ITV she said: "Precisely how we calculate that increase will be a matter for the manifesto."
The triple lock currently guarantees pensions will increase by either the pace of inflation, average earnings, or 2.5 per cent, whichever is the higher. It was introduced in 2010 by the Conservative party under David Cameron before that year's General Election, before being pledged again in 2015.
In practice inflation and wage increases have both remained weak since then, meaning pensioners have enjoyed increases in their real income that have far outstripped most of the rest of the country.
Some members of the Conservative party have suggested an alternative "double lock", dropping the pledge to increase the pension by 2.5 per cent each year.
Labour has promised to retain the triple lock until 2025 at least, but ministers reportedly want to scrap the pledge because of the rising cost of the policy.
The Government Actuary's Department has stated the policy cost £6bn last year, although with inflation set to increase to as much as 2.7 per cent this year by the Bank of England the cost of the 2.5 per cent commitment is likely to fall.
May earlier promised the Conservative party will not raise VAT, but refused to re-commit to the "tax lock" made by former Prime Minister David Cameron that income tax, national insurance or VAT will not rise.