Sir Keir Starmer is visiting the White House where he will meet US President Joe Biden to discuss conflicts in Ukraine and Gaza.
During the trip, he admitted there had been no impact assessment of how the decision to cut winter fuel payments will affect millions of pensioners.
However, the new measures have cost him points in favourability ratings as a new Ipsos poll found 46 per cent of people see him unfavourably, an eight-point increase in three months.
Chancellor Rachel Reeves, who has also been pressured over the upcoming October Budget, has seen her favourability fall by four points to 23 per cent.
The prime minister and Mr Biden are expected to consider Kyiv’s request to be able to use Western Storm Shadow long-range missiles in Russian territory.
But President Putin said such a move would mean that Russia would be “at war with Nato”.
Speaking to reporters during a flight to Washington DC, Sir Keir said Russia started the conflict in Ukraine and that it can end the war “straight away”.
