LONDON, U.K.: British Prime Minister Keir Starmer won a vote in Parliament this week to move ahead with changes to the country's welfare system. However, the win came at a high political cost.

He faced the largest rebellion from his own Labor Party since becoming prime minister.

A total of 49 Labor members of Parliament voted against the welfare reforms. This shows that many in his party are unhappy and that Starmer is losing some control. Even though he has a large majority in Parliament, he was forced to backtrack on key parts of the plan.

Starmer had promised that his substantial majority would bring stability after years of political chaos under the Conservative government. But the problems surrounding this welfare bill show how difficult it is to pass unpopular policies.

The government initially wanted to save about £5 billion a year by tightening the rules for who can receive disability and sickness benefits. These changes were meant to help reduce the growing cost of the welfare system, which the government says is not sustainable. The cost of these benefits is expected to reach over £100 billion by 2030, more than the defence budget.

However, after pressure from within his party, the government made significant changes to the plan. One big change was that the new rules would only apply to future applicants, not people already getting the benefits. This could reduce the savings to around £2 billion a year.

Some Labor MPs were very critical. Paula Barker said the way the plans were handled was "the most unedifying spectacle" she had ever seen. Others said the prime minister was right to listen to the criticism. Henry Tufnell said Starmer showed he was open to feedback by making changes.

Ministers and party officials worked hard in the hours before the vote to convince unsure MPs to support the plan. Just two hours before the vote, the government made another concession, agreeing to delay changes to a key benefit until a full review was finished.

Disability and human rights groups also opposed the reforms. Nearly 90 of them urged MPs to vote against the bill.

After the vote, opposition parties said the government had lost control and only won by watering down its original plan. They also warned that the government may now have to raise taxes or cut spending elsewhere in the next budget.

Though Starmer is not in immediate danger of losing power, polls show his popularity is falling. Polling expert John Curtice recently said Starmer is now the most unpopular elected prime minister in modern British history.