Nicholas Soames, the grandson of Britain's World War Two leader Winston Churchill, said he would vote against Prime Minister Boris Johnson on Brexit on Tuesday, a step that enforcers have warned would lead to expulsion from the Conservative Party.

Mr. Johnson's party has warned lawmakers they will be expelled if they vote against the government and seize control of parliamentary business in a bid to force a Brexit delay.

Among more than a dozen pro-EU Conservative lawmakers who have indicated they may rebel against the government are Ken Clarke, 79, the longest continuously sitting British lawmaker in the House of Commons, who was finance minister under Prime Minister John Major, and former finance minister Philip Hammond.

“I will be voting against the government tonight with a very heavy heart,” Mr. Soames said.

Mr. Johnson has shown ruthlessness since he took office as prime minister six weeks ago: He oversaw one of the biggest purges of cabinet ministers in modern British history and has cut short a session of parliament to increase the likelihood Britain will leave the EU, with or without a deal.

Soames, 71, who was knighted by Queen Elizabeth in 2014, has been a member of parliament since 1983 and previously served as a junior defence minister. He is the son of Mary Soames, the youngest of Churchill's five children.

Churchill occupies a special place in British culture as the victor of World War Two and by far the most powerful British statesman of the 20th Century - a British bulldog who could hold his own with Josef Stalin and Harry Truman.

Mr. Johnson has repeatedly spoken of his admiration for Churchill, and in 2014 published a biography called “The Churchill Factor: How One Man Made History.”

In the introduction, Mr. Johnson, then mayor of London, wrote: ”When I was growing up there was no doubt about it. Churchill was quite the greatest statesman that Britain had ever produced.”

Andrew Adonis, a member of the opposition Labour Party, said Churchill would have deselected from Conservative if it was run like it is now because he opposed then prime minister Neville Chamberlain attempt to secure peace with Germanys Adolf Hitler a year before World War Two.

“Churchill himself would have been deselected,” he said. “Chamberlain bitterly attacked him for undermining his negotiating position at Munich and there was a deselection attempt.”