Foreign Secretary James Cleverley said he could not give people “certainty” on how much their pensions would rise by next year.
State pensions are due to rise by almost 10% in April 2023, taking the weekly payment from £185.15 to more than £200.
But the funding formula that guarantees those increases — known as the “triple lock” — could be eliminated to make savings.
It comes as Liz Truss prepares to face MPs at Prime Minister’s Queries.
It was the first time the prime minister faced questions from MPs after nearly the entire economic program was pitched by new chancellor Jeremy Hunt on Monday.
She sat in silence on Tuesday as Mr. Hunt laid out his plans in the Commons and ignored calls from the opponent to answer questions.
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The PM’s team thinks her engagement with MPs this week has warmed and her position has enhanced, with Ms. Truss still under severe pressure as her authority weakens after abandoning her flagship policies.
An ally of the PM said she was determined to keep the job, but her battle for survival would play out in public by midday when she would face questions in parliament from Labor and her own backbenchers.
A poor performance at PMQs could convince more of Ms Truss’s MPs that they need to get rid of her quickly.
Many of the government’s tax and spending plans are in doubt ahead of an announcement on October 31.
Pensions: Minister unable to clarify on the triple lock
It also includes a “triple lock” on pensions, which guarantees that payments will rise the higher – prices, and average wages or 2.5%.
Asked if the government was still committed to the triple lock, Mr Wise told the BBC breakfast ministers took manifesto commitments “incredibly seriously”.
“I know that your viewers want me to be sure here and now. I am not in a position to do that because there is going to be informed by the chancellor very soon,” he said.
“We have to do the right thing to make sure that we manage the economy well. We have to make sure that our cost of borrowing doesn’t go up because that affects inflation and those bills as well.”
New Chancellor Jeremy Hunt is due to announce the government’s plans for tax and spending on October 31.
All government branches have been told to find savings and Mr. Hunt has not ruled out further tax rises and spending cuts to reassure financial markets and keep UK debt under control.
Inflation – the rate of growth in prices – is running at a 40-year high of 10.1%, meaning wages, pensions and gifts are not keeping up with the cost of living.
A decision on how much to increase pensions has yet to be made by next April and is usually expected this autumn.
Apart from a one-year suspension during the pandemic, the triple lock has been in place since it was introduced under the Conservative-Liberal Democrat coalition.
The Resolution Foundation think tank calculates that increasing pensions by earnings instead of inflation could save the government £6bn next year.
The government has declined to commit to increasing benefits in line with inflation, a pledge made by Ms. Truss’ prototype Boris Johnson. The issue dominated the Tory party conference in Birmingham – and the breach of previous promises on pensions and advantages is likely to face resistance from many Tory MPs.
Previously supportive newspapers, the Daily Mail and the Daily Express, also took to their front pages on Wednesday to attack the Prime Minister for not adhering to the triple lock.
They are committed to keeping labor pensions under triple lock.