Sir Keir Starmer had a series of one-on-one meetings with Labour MPs on Friday to try to contain a rebellion on the government's welfare reforms.
Ahead of the assisted dying vote, the prime minister met privately with some of the dozens of MPs with concerns about the proposed cuts to sickness and disability benefits.
The first vote on the legislation, which the chancellor says will save £5bn a year from the welfare bill, will be held in early July.
The prime minister's involvement at this stage suggests a major effort is underway to quell a potential rebellion.
Cabinet ministers say they do not expect mass resignations, but one junior minister told Sky News that opposition to the reforms was "pretty strong".
One frontbencher, government whip Vicky Foxcroft, resigned her post yesterday, writing that she understood "the need to address the ever-increasing welfare bill" but did not believe the proposed cuts "should be part of the solution".
Other junior ministers and whips have not, as yet, moved to follow her. But one government insider said: "It's difficult to tell if the mood will harden as we get closer. There's a lot of work going on."
The package of reforms is aimed at encouraging more people off sickness benefits and into work, but dozens of Labour rebels said last month that the proposals were "impossible to support".
Welfare secretary Liz Kendall is also meeting individually with MPs.
She said earlier this week that the welfare system is "at a crossroads" and the bill was about "compassion, opportunity and dignity".
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Ministers are trying to convince MPs that a £1bn fund to support disabled people into work, and the scrapping of the Work Capability Assessment, a key demand of disability groups, make the cuts package worth voting for.
They insist that 90% of current claimants of personal independence payment (PIP) will not lose the benefit.
But disability groups say the cuts will have a "disastrous" effect on vulnerable people.
(c) Sky News 2025: Sir Keir Starmer tries to contain rebellion among Labour MPs over welfare reforms
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