Liberal Democrat leader Vince Cable walks with pro-EU demonstrators on a march through central London during the People's March for Europe on September 9, 2017 | Niklas Hallen/AFP via Getty Images Vince Cable calls for Boris Johnson to be sacked The Liberal Democrat leader criticized the foreign secretary for being ‘volatile’ with ‘Trump-like characteristics.’

Liberal Democrat leader Vince Cable lamented "the complete breakdown of discipline" in Theresa May's Cabinet Monday and said that Foreign Secretary Boris Johnson should "absolutely" be fired from his job.

Speaking to the BBC's Today program, Cable criticized Johnson's 4,000-word treatise on Brexit in the Telegraph over the weekend in which the foreign secretary repeated the discredited call for £350 million a week that is currently sent to the EU to be spent on the NHS post-Brexit. “Once we have settled our accounts, we will take back control of roughly £350 million per week. It would be a fine thing, as many of us have pointed out, if a lot of that money went on the NHS," Johnson wrote.

"What has made his [Johnson's] position impossible is that he is not just being contradicted by politicians ... but by senior civil servants," Cable said, referring to David Norgrove, the U.K. Statistics Authority chief who debunked the numbers Johnson presented. "This is simply wrong."

"Even [former UKIP leader] Nigel Farage disowned it [the £350 million figure]," Cable added. "Why he's gone back to it is just extraordinary."

Asked whether Johnson could become the next prime minister, Cable said: "He could well be. He clearly is extremely volatile, unpredictable, very sort of Trump-like characteristics here, the very opposite of Theresa May."