Just under a year ago, Keir Starmer strode into Downing Street with cheers ringing his ears, having won a landslide victory.
But tonight he found that having a massive majority isn't always enough.
Downing Street underestimated how strongly backbenchers opposed these cuts, despite the clear warning signs.
For months I'd been hearing how unhappy MPs were, concerns echoed by Labour's trade union backers, party members and Mirror readers.
Most Labour MPs accept the welfare bill is too high, and agree that people need help to get back into work.
But the PM and his ministers failed to convince them that cutting Personal Independence Payments - an in-work benefit - was the way to achieve this.
The Government blew a lot of political capital on its disastrous decision to cut the winter fuel allowance.
And the recent U-turn gave Labour MPs hope that they could persuade the PM into another rethink.
The decision will be some relief for hundreds of thousands of disabled people left terrified about what cuts to these lifeline benefits would mean.
But making these concessions is a major blow to Mr Starmer's authority - particularly so early on in premiership.
One of the PM's biggest problems is the disconnect between what the Government is doing - and what the voters thought they were getting.
Plenty of Labour MPs feel that they didn't sign up to take disability benefits from vulnerable people.
And they've been left to face angry constituents who think this wasn't what they voted for.
Another problem has been Mr Starmer has been forced to dedicate so much attention to foreign affairs.
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A senior figure in No10 expressed frustration to me that he had to go to both the G7 summit in Canada and the NATO gathering in the Netherlands in quick succession, when they needed him in London.
After arriving back on Wednesday night, Mr Starmer spent much of today locked in talks with backbenchers to avert a damaging Commons defeat next week. Time will tell if the offer made to rebels is enough.
Mr Starmer has been dealt a difficult hand, with Donald Trump causing chaos and tensions spiralling in the Middle East.
But he must bear responsibility for problems at home - and pointing to the dire Tory legacy won't cut it any more.