LONDON - Prominent Brexit supporter Andrea Leadsom resigned from Prime Minister Theresa May's government on Wednesday, piling pressure on the British leader after a new Brexit gambit backfired and fuelled calls for her to quit.

So far May has resisted, vowing to press on despite opposition from lawmakers and other ministers to her bid to get her Brexit deal through parliament by softening her stance on a second referendum and customs arrangements.

But Leadsom's resignation further deepens the Brexit crisis, sapping an already weak leader of her authority. Almost three years since Britain voted to leave the European Union, it is not clear when, how or even if Brexit will happen.

Leadsom, Leader of the House of Commons, said she could not announce the new Withdrawal Agreement Bill, which will implement Britain's departure, in parliament on Thursday as she did not believe in it.

"I no longer believe that our approach will deliver on the referendum result," Leadsom, once a challenger to May to become prime minister, said in a resignation letter.

"It is therefore with great regret and with a heavy heart that I resign from the government."

A Downing Street spokesman praised Leadsom and expressed disappointment at her decision, but added: "The prime minister remains focused on delivering the Brexit people voted for."

May might still try to press on with her new Brexit plan, which includes a vote on whether to hold a second Brexit referendum -- once her legislation passes the first stage -- as well as closer trading arrangements with the EU.

But it has been met with a swift backlash, with several lawmakers who have supported her in previous Brexit votes saying they could not back the new plan, particularly over her U-turn regarding a possible second referendum.

"I have always maintained that a second referendum would be dangerously divisive, and I do not support the government willingly facilitating such a concession," Leadsom said.

"No one has wanted you to succeed more than I have," Leadsom wrote to May. "But I do now urge you to make the right decisions in the interests of the country, this government and our party."

Labour lawmaker Ian Lavery, chair of the opposition party, said the resignation underlined that "the prime minister's authority is shot and her time is up".
"For the sake of the country, Theresa May needs to go, and we need an immediate general election," he said.