Theresa May failed to guarantee that her Conservative government would keep the state pension triple-lock when she was grilled on the issue during Prime Minister's Questions (PMQs) on Wednesday 26 April.
The Tory premier, speaking with just over six weeks to go before the 8 June general election, only decided to defend her party's record in power instead.
"The party in government that has improved the lot of pensioners is the Conservatives," she said.
But SNP deputy leader Angus Robertson put May under increased pressure over the policy, which increases the value of the state pension by inflation, average earnings or at least 2.5%.
"I asked the prime minister a pretty simple question. It's a 'yes' or a 'no' and the prime minister failed to answer," he said. "So pensioners right across this land are right to conclude that this Tory prime minister plans to ditch the triple-lock guarantee on state pensions."
May's reluctance to back the triple-lock could see the Conservatives lose votes from older people at the general election. Labour Shadow Chancellor John McDonnell has already committed his party to the policy.
"May's refusal to commit the Tories to maintaining the pensions triple lock only further proves the Tories are abandoning older people. It's now clear pensions protections are now in jeopardy," he said.
"Labour will stand up for older people by maintaining the pensions triple-lock and by keeping the winter fuel allowance and free bus passes so that the elderly can go about their lives with the dignity they deserve."
Elsewhere, PMQs was expectantly dominated by election slogans, with May warning against a "coalition of chaos" and raising the importance of "strong and stable leadership", whilst Corbyn campaigned against a "rigged system" and claimed the Tories were for "the rich not the rest".
The latest opinion poll from Ipsos MORI, of more than 1,000 people between 21 and 25 April, gave the Conservatives a 23 point lead over Labour (49% versus 26%).