(Bloomberg) -- Follow @Brexit on Twitter, join our Facebook group and sign up to our Brexit Bulletin.

Boris Johnson will face a tough fight from political heavyweights if he tries to suspend Parliament to force through a no-deal Brexit.

Anti-Brexit campaigner Gina Miller and Work and Pensions Secretary Amber Rudd both opposed the idea on Sunday, adding to growing ranks across the political divide who say they are concerned about upholding Britain’s constitution.

Miller, who already took the government to court to force it to get Parliamentary approval before beginning Brexit talks, said she’s assembling the same team to launch immediate legal action should Johnson try to shut down Parliament if he prevails as leader.

“It would be an abuse of his powers to close Parliament” and “limit the voice of the representatives that we all elect,” Miller said, speaking on the Sophy Ridge on Sunday show on Sky. Her team would be “actively defending Parliamentary sovereignty, because it is the cornerstone of our constitution,” she said.

Johnson, the favorite to succeed Prime Minister Theresa May this month, has pledged to take Britain out of the European Union with or without a deal on Oct. 31. He’s refused to rule out proroguing -- or suspending -- Parliament to fulfill that pledge.

Former Prime Minister John Major has already said he would be ready to take the government to court if the incoming leader tries to prorogue Parliament, a position Chancellor of the Exchequer Philip Hammond has also backed. Rudd told the BBC on Sunday that she respects Major’s position and that shutting Parliament “would be the wrong thing to do and I would always argue against it.”

Johnson could still find some support among Conservative Party lawmakers.

“This should not be about the semantics of Parliament or proroguing Parliament, we now have to get behind a new government that is very clear in a future determination now, which is to get out of the European Union come what may,” former cabinet minister Priti Patel said on Sky.

The power to suspend Parliament lies with the monarch at the request of the prime minister, which could leave Queen Elizabeth II in a tricky situation. One of the long-standing goals of both Buckingham Palace officials and government civil servants has been to keep the monarch out of any political controversy.

To contact the reporter on this story: Jill Ward in London at jward98@bloomberg.net

To contact the editors responsible for this story: Fergal O'Brien at fobrien@bloomberg.net, Cecile Gutscher, James Amott

©2019 Bloomberg L.P.