Theresa May is under pressure to spell out her plans for pensions, after failing to commit the Conservatives to preserving the "triple lock" guarantee after the general election.
Elsewhere, Chancellor Philip Hammond suggested he wants the upcoming Tory manifesto to drop the party's pledge from the 2015 election not to raise income tax, national insurance or VAT over the life of the next Parliament.
Speaking in Washington DC, the Chancellor told the BBC: "All chancellors would prefer to have more flexibility in how they manage the economy and how they manage the overall tax burden down (rather) than having to have their hands constrained.
"But what we put in the manifesto will be decided in the next few days and we will publish that."
The Liberal Democrats accused the Conservatives of "getting their betrayal in early", while Labour leader Jeremy Corbyn highlighted the contrast between Mrs May's silence on pensions with his own party's commitment to keep the triple lock, which guarantees payments will rise annually by the highest of inflation, average earnings or 2.5% each year.
Mrs May was asked during a visit to a factory in her Maidenhead constituency whether older people can expect to see their pensions continue to rise, if she wins the election, as they have done so far under Conservative-led administrations.
She replied: "What I would say to pensioners is, just look what the Conservatives in government have done. Pensioners today are £1,250 better off as a result of action that has been taken.
"We were very clear about the need to support people in their old age, and that's exactly what we've done."
The prime minister was more willing to make her position clear on aid, following calls from charities and philanthropist Bill Gates for her to continue meeting the United Nations target enshrined in law by predecessor David Cameron.
"Let's be clear, the 0.7% commitment remains and will remain," said Mrs May.
Shadow chancellor John McDonnell said: "Theresa 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.
"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."
Liberal Democrat frontbencher Alistair Carmichael said pensioners "should now realise that their pensions are not safe in Conservative hands".
"This is May and Hammond admitting that the cupboard is bare thanks to their disastrous hard Brexit," said Mr Carmichael.
"Theresa May's refusal to guarantee the triple lock is yet another massive U-turn by the Prime Minister. Conservative high command is clearly in total disarray as it attempts a handbrake turn every day, including on such major issues as immigration, foreign aid and the single market."
The aid announcement was welcomed by charities, who issued a joint statement saying they were "delighted that the Prime Minister has recommitted to spending 0.7% of national income on aid and clearly stated her belief that aid saves and changes lives".
But Mrs May came under attack from Ukip leader Paul Nuttall who said it was an "absolute outrage" that aid spending would now rise to £15 billion by 2020.
"We want to see British taxpayers' money spent here in our country on our own people. We are not afraid to say 'charity begins at home'," said Mr Nuttall.