LONDON (TIP): Indian-origin Conservative party lawmaker and former UK Cabinet minister Priti Patel has joined the race along with 20 other party rebels who are challenging British Prime Minister Theresa May‘s Brexit strategy with a ‘Stand Up 4 Brexit’ campaign.

The grassroots drive against any negotiations with the European Union (EU) that could lead to a so-called soft Brexit is being backed by another ex-minister Ian Duncan Smith and is expected to mount pressure on May to ditch her Chequers plan, which is rejected by Eurosceptic lawmakers within her Conservative party.

‘Stand Up 4 Brexit’ supporters, who also include former foreign secretary Boris Johnson’s key ally Tory lawmaker Conor Burns, pledge to fight plans to keep the EU rules on British goods and free movement in terms of migration.

Ms Patel, a leading pro-Brexit voice in the lead up to the referendum in favor of Britain’s exit from the EU in June 2016, has previously called on the government to be “tougher” in its negotiations with Brussels.

The Stand Up 4 Brexit campaign is building momentum as Mr Johnson, the poster boy for the pro-Brexit camp, launched a scathing attack on Theresa May’s plans in his weekly newspaper column in ‘The Daily Telegraph’ on Monday, saying the approach agreed at Chequers “means disaster” for Britain.

Mr Johnson said negotiations based on the Chequers plan had so far seen the EU take “every important trick”, adding, “The UK has agreed to hand over GBP 40 billion of taxpayers’ money for two-thirds of diddly squat [nothing].”

The so-called Chequers plan put forth by PM May would see Britain agreeing a “common rulebook” with the European Union for trading in goods, in an attempt to maintain frictionless trade at the border.

Critics of the strategy argue this would leave the UK tied to the EU rules even after it formally leaves the economic bloc on March 29 next year and prevent Britain from striking its own trade deals in years to come.

As the UK’s parliamentary recess period of August comes to an end and the political parties in the country prepare for their annual party conferences this month, the battle lines around Brexit are expected to deepen further.

Even after the UK and the EU have reached some sort of an agreement over their future trading relationship, any agreed plan will then be tabled before lawmakers for a vote – a process which will be accompanied with its own share of upheavals.