The triple-lock protection for state pensions should be abolished, the former junior minister responsible for the benefits has urged.
Baroness Altmann, who left her post as pensions minister in the reshuffle, warned the cost of keeping the safeguard in place would be "enormous" after 2020.
The Tory peer said she tried to persuade then PM David Cameron to drop the triple lock, which sees pensions rise by the inflation rate, average earnings or a 2.5% safety net - whichever is the highest - last year, but he refused for political reasons.
"The triple lock is a political construct, a totemic policy that is easy for politicians to trumpet, but from a pure policy perspective keeping it forever doesn't make sense," Lady Altmann told The Observer.
"I was proposing a double lock whereby either you increase state pensions in line with prices or with earnings.
"Absolutely we must protect pensioner incomes, but the 2.5% bit doesn't make sense. If, for example, we went into a period of deflation where everything, both earnings and prices was falling, then putting up pensions by 2.5% is a bit out of all proportion.
"Politically, nobody had the courage to stand up and say we have done what we needed to do."
The ex-minister believes the triple lock could be abandoned now Theresa May is Prime Minister, the newspaper reports.
Mrs May's joint chief of staff Nick Timothy said in an article for Conservative Home last November that the "obvious alternative" to welfare credit cuts - looking at the triple lock - was "off the table" for then chancellor George Osborne.
"He could redistribute the welfare cuts to take the pressure off low-paid, working people. But the obvious alternative is already off the table: pensioner benefits are protected and so is the 'triple lock', which means that the state pension goes up by the highest out of the growth of wages, inflation or 2.5%," Mr Timothy wrote.
The Department for Work and Pensions told the Press Association it did not comment on speculation.