LONDON: British Prime Minister David Cameron is seeking to impose discipline on his warring Conservative Party Monday, after a Cabinet resignation — ostensibly about unpopular welfare reforms — blew the top off simmering divisions over the European Union.

Work and Pensions Secretary Iain Duncan Smith, who has pushed through big changes to the country's welfare system over the past six years, dramatically quit late Friday, accusing the government of targeting the poor for cuts while protecting pensions for the better-off.

"I am passionate about trying to improve the quality of life for those in difficult circumstances," Duncan Smith said Sunday. "Now, I want to do that and I want my party to do that. But I felt that I'm losing my ability to influence that."

The resignation of Duncan Smith — a former Conservative leader whose nickname when at the helm between 2001 and 2003 was "The Quiet Man" — has set off a firestorm in his party for reasons that have little to do with welfare reform.

Duncan Smith is among a group of senior Conservatives who want Britain to leave the European Union, and his resignation has heaped pressure on Cameron and Treasury Chief George Osborne — both of whom want the UK to stay in the EU. The country will decide in a June 23 referendum whether to remain in the 28-nation bloc.

Tim Bale, professor of politics at Queen Mary University of London, said Duncan Smith's move would bolster the "out" campaign.

"I think it reinforces the public view that David Cameron and George Osborne appear to be disconnected from public opinion," he said. Bale added that the Duncan Smith's accusations add to a perception that Cameron and Osborne are "taking from the poor and disabled and giving to the rich."

Duncan Smith's resignation was followed by a series of strikingly barbed and partisan remarks as senior Tories blamed one another for the mess. Pensions Minister Ros Altmann, who worked under Duncan Smith, accused him of wanting "to do maximum damage to the party leadership in order to further his campaign to try to get Britain to leave the EU."

But Employment Minister Priti Patel said Duncan Smith had resigned because he was "extremely passionate about the principle of social justice."

"I fundamentally believe that this is not about Europe," she told the BBC.

Cameron — who has staked his political future on getting voters to remain in the EU — is due to report to the House of Commons Monday afternoon about last week's migration summit in Brussels. But the session will likely be dominated by welfare cuts and Europe — an issue that has divided the Conservatives since Britain joined the EU in the 1970s.

The row is a blow to Osborne, who has been Treasury chief since 2010 and aspires to succeed Cameron as Conservative leader.

Since taking office in 2010, Osborne's primary economic policy has been to reduce Britain's deficit through a cocktail of spending cuts and tax increases. In last week's latest austerity budget, Osborne announced plans to cut 33 billion pounds ($48 billion) from welfare spending by 2020, including around 4 billion pounds from disability payments.

Duncan Smith's replacement, Stephen Crabb, is expected to announce that the government is dropping the budget's most contentious welfare reform, the reduction in disabled benefits.

The government has stressed that its austerity medicine has been shared fairly across all income brackets — its mantra has been "we're all in this together."

But Duncan Smith said pensions, which account for more than half of total welfare payments, have been untouched while billions had been cut from benefits paid to working-age people.

He said it gave the impression that the government did not care about the working poor, "because they don't vote for us."

Duncan Smith's resignation drew support from some Conservatives — chiefly those who back a so-called "Brexit" from the EU.

Conservative lawmaker Sarah Wollaston told the BBC that Osborne should revise his budget decisions because there was a perception that the ax was falling harder on the poor and the disabled than on other segments of society, notably pensioners.

"The point that Iain Duncan Smith was making was that there are some groups at the moment that can't be touched," she said. "If we are going to have inter-generational fairness that might mean looking at where that might fall."

The row at the top of the government weighed on the British pound. In early afternoon trading in London, it was down 0.5 percent at $1.4395.

Kit Juckes, foreign exchange strategist at Societe Generale, said the resignation of Duncan Smith adds "another layer of political risk" to the pound.

"Politics is going to be more important than economics for the next three months," he said.