Getting nowhere in proving treason through campaign connections to Russia, the latest attempt to remove President Donald Trump from office is a movement to invoke the 25th Amendment. Because the Constitution as it is written really isn't taught in public schools anymore, you probably didn't know that the 25th codifies the procedure for replacing the President in case of incapacitation or death. Until 1967, there was no official procedure to pass on power from the President to the Vice President.
The provision that those on the left want to invoke in the case of President Trump is Section 4--which allows the Vice President or the Cabinet to inform the Congress that the President is unable to discharge his duties anymore--and that the Vice President should be granted his powers. However, if the President notifies Congress that he is in fact able to discharge his duties--he remains in power. But if the Veep or the Cabinet comes back within four days to say "no, this guy is not fit to hold the office", Congress must immediately convene and vote on who should be President within 21-days. If they vote the President out, the Vice President moves up. If they vote to keep the President--or take no action in three week--he stays.
Obviously, the 25th Amendment was drafted to deal with situations where Presidents become physically incapacitated due to assassination attempts or medical emergencies. There was real concern after Woodrow Wilson suffered a stroke in his second term (and his wife effectively ran the White House) and with Franklin Roosevelt's deteriorating health during his fourth term. That was compounded by the chaos in the hours after John Kennedy was shot (and Lyndon Johnson could have been too) that precipitated drafting of the 25th to clean up the succession process.
I don't think that Congress at the time thought it would be used to claim that the President is a crazy man that needs to be removed from office. Imagine what it would be like if Mike Pence or the Cabinet did alert Congress that President Trump is unable to discharge his duties. Trump would certainly fire back notice that he is more than fit to lead--and then would unleash a barrage of Twitter posts attacking Pence and said Cabinet members as being the "real crazy people".
If Pence came back with a second notice, you would have Congress forced to hold hearings into the mental fitness of President Trump. Employers across the country would be best off to just close all businesses if that happens--because that will be must see TV all day, every day. Psychiatrists, psycholgists and sociologist would all be called to testify--nearly all of them just guessing as to the President's mental state--as he would allow just one doctor to conduct a test that will guaranteed find him to be sane. And then to have open debate on the mental state of the President on the House floor? You can bet we will be pre-empting all regular programming for that as well.
But in the end, unless Trump were to rise from his chair and imitate Doctor Strangelove at the end of Stanley Kubrick's classic movie and be unable to control his "Nazi arm", Congress will not vote to invoke the 25th Amendment--guaranteeing us at least another three years of the most bizarre period in US political history.