Donald Trump faced fresh calls for his removal from the White House after his sexist Twitter rant about a TV host.

The US President's opponents suggested an often-overlooked section of the US constitution could provide grounds for removing him from office following his personal attack on TV host Mika Brzezinski.

Mr Trump has endured calls for his impeachment since his election, but the latest outburst prompted critics to turn to an alternative means of stripping him of power amid questions over his fitness to govern.

The fourth clause of the constitution's 25th amendment allows a President who is "unable to discharge the powers and duties of his office" to be removed.

MSNBC's Mika Brzezinski responds to Donald Trump's attack

Conceived during the Cold War, the section was intended to provide a safeguard if the President fell ill, died or became incapacitated. Its introduction came after President Eisenhower was stricken with serious illnesses and President Kennedy was assassinated.

But some have speculated the 25th amendment could allow Congress evaluate the President’s fitness for office without impeaching him.

The clause reads: "Whenever the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide... their written declaration that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President".

Two students at a top US law school argued in March that the little-known amendment allows Congress to form its own body to evaluate the President’s fitness for office without impeaching him.

And the prospect reared its head again amid outrage at Trump's personal attack on Morning Joe presenter Ms Brzezinski, who he claimed he had seen "bleeding badly from a face-lift".

Bill Burton, deputy press secretary at the White House under Barack Obama, tweeted: "In any other presidency this would be cause to trigger the 25th amendment. But in 2017, this is normal."

Other Trump critics cited the 25th amendment on social media.

Keith Olbermann, special correspondent at GQ, said Mr Trump's "irresponsible speech" was "destroying this country" and suggested the President was mentally "self-destructing".

He called on Republican senators to "help invoke Section 4 of the 25th Amendment and remove Trump," adding: "Do it today."

But lawyers said the fourth section of the 25th amendment, which has never been used before, was unlikely to prise Mr Trump from his seat at the White House.

Joel K. Goldstein, writing in the Washington Post, said: "The bar for Congress declaring the President disabled is high. The president resumes power unless two-thirds in each chamber conclude he or she 'is unable' to handle the office."

Mr Trump's tweets about the Morning Joe host have been widely condemned both by his opponents and members of the Republican party.

Ms Brzezinski and co-host Joe Scarborough also responded with a joint op-ed article in which they wrote: "President Trump launched personal attacks against us Thursday, but our concerns about his unmoored behaviour go far beyond the personal.