PM at a tipping point as he seeks to avoid humiliation by his own MPs
We've just been hearing from our political editor Beth Rigby, who is with the prime minister at the NATO summit in The Hague, about his welfare versus warfare dilemma.
Beth says: "What you have here is a prime minister here at NATO with a national security review warning of potential threats to the UK, a prime minister saying his first duty is the defence and security of my people, and saying simply he has to increase defence spending."
The pledge to spend 5% of GDP on defence and security by 2035 would add around 拢30bn to the government's current spending commitment, she explains.
"It is a huge amount of money. They haven't said yet how they will fund that, but what you're clearly seeing is a prime minister who has to make choices about where to spend money."
The other competing element is welfare, which European states have spent more on at the cost of defence after the Cold War ended.
Beth says: "We're at a tipping point here, with the prime minister clearly saying he has to put the money into warfare, into defence - it's not particularly popular with voters who would prefer more spending on public services.
"The problem he's got in the short term is the welfare legislation cuts 拢5bn from the overall bill, hitting PIP payments, with his MPs in full-blown rebellion."
Starmer in a horrible position
That, she explains, is why she asked if the vote on the welfare reforms is effectively a confidence vote, because "how humiliating would it be if, but a year into being prime minister with a landslide majority, [he] was defeated on a flagship policy".
"It is a horrible position for him to be in," Beth says, which is why he told her it is not a confidence vote, and he will press on, because "what option does the government have".
"People today are telling me that financially they can't back down because they need to find the savings, and politically, they cannot back down because it looks weak."
The only option is to whittle down the rebellion - but that has only grown today.
"He is a prime minister is a really difficult position in the next few days in this welfare versus warfare debate."