Senator leading Russia investigation sets odds of Trump impeachment at 2-to-1

President Donald Trump is deeply unpopular, and he's facing probes of his campaign ties to Russia and a myriad of ethical questions about his family business -- which could eventually prompt Republican lawmakers to dump him.

Trump's critics are already exploring impeachment or the invocation of the 25th Amendment, which allows the replacement of presidents who are deemed mentally unfit, and some lawmakers and other experts believe he's unlikely to finish his term, reported The New Yorker.

His approval rating has drooped to 40 percent -- the lowest for any newly elected president since Gallup began measuring it -- and the FBI and four congressional committees are investigating alleged collusion between his associates and the Russian government.

"You can’t govern this country with a forty-per-cent approval rate -- you just can’t," Stephen Moore, a senior economist at the Heritage Foundation and Trump campaign adviser, told the magazine. "Nobody in either party is going to bend over backwards for Trump if over half the country doesn’t approve of him. That, to me, should be a big warning sign."

The president has faced criticism for hiring his daughter and son-in-law as senior advisers, and a federal lawsuit has been filed accusing Trump of violating the Constitution's emoluments clause by retaining ownership of hotels, golf courses and other real estate developments around the world.

"The reality is, he is governing as if he is the president of a Third World country," said Jerry Taylor, president of the libertarian Niskanen Center. "Power is held by family and incompetent loyalists whose main calling card is the fact that Donald Trump can trust them, not whether they have any expertise."

Sen. Mark Warner (D-VA), the ranking Democrat on the Senate Intelligence Committee, has privately told friends that he sets the odds at 2-to-1 that Trump will not complete his full term -- although he told The New Yorker he was not referring specifically to the Russia probe.

"My guess is that there’s only between 50 and 100 Republican members of the House that are truly enthusiastic about Donald Trump as president," said Taylor, head of the libertarian think tank. "The balance sees him as somewhere between a deep and dangerous embarrassment and a threat to the Constitution."

Several lawmakers have questioned Trump's mental capacity, and bills have been introduced in both the House and Senate that would give medical professionals more authority in assessing a president's fitness -- and not everyone agrees that invoking the 25th Amendment is more than a "liberal fantasy."

"I believe that invoking Section 4 of the 25th Amendment is no fantasy but an entirely plausible tool," said Laurence Tribe, professor of constitutional law at Harvard Law School. "Not immediately, but well before 2020.”