British Prime Minister Theresa May says she sees no alternative to the Brexit deal she presented earlier this week, amid reports that some of her senior ministers want her to renegotiate the draft agreement before meeting EU leaders next weekend.

“There is no alternative plan on the table. There is no different approach that we could agree with the EU,” May wrote in an article for the Sun on Sunday newspaper.

Just hours after announcing on Wednesday that her senior ministers had collectively backed her divorce deal, May was thrust into her premiership’s most perilous crisis when Brexit Secretary Dominic Raab resigned on Thursday to oppose the agreement.

Other mutinous lawmakers in her party have openly spoken of ousting her and said the Brexit deal would not pass parliament.

On Saturday Andrea Leadsom, the minister in charge of government business in parliament, told the BBC that she was supporting May but was not fully happy with the deal.

“I think there’s still the potential to improve on the clarification and on some of the measures within it and that’s what I’m hoping to be able to help with,” she said.

Ireland’s foreign minister, Simon Coveney, said on Saturday that British pro-Brexit ministers were “not living in the real world” if they thought they could renegotiate the divorce treaty agreed with the EU last week.

Several British newspapers had reported that Leadsom was working with four other senior ministers and Brexit enthusiasts Michael Gove, Liam Fox, Chris Grayling and Penny Mordaunt to pressure May to change the deal.