One of the most stable aspects of Donald Trump's presidency has been his approval rating. According to Gallup, Trump's floor has been 35 percent while his ceiling is just ten points higher at 45 percent. Gallup notes the 10-point range is "the smallest for any president during his first two years in the Oval Office by a significant margin."
The president with the second most narrow variation was Richard Nixon at 16 points, with approvals ranging between 51 and 67 percent. Nixon's average approval rating, 59 percent, was also quite high relative to Trump's. In fact, he entered his second term with a soaring 68 percent approval rating in January 1973. But that spring, news of the Watergate scandal began coming to light and Nixon’s approvals collapsed.
Pew Research writes: “By April, a resounding 83% of the American public had heard or read about Watergate, as the president accepted the resignations of his top aides John Ehrlichman and H.R. Haldeman. And in turn, Nixon’s approval ratings fell to 48%.”
The televised Watergate hearings began in May and by August, Nixon had just 31 percent support of the country. It was almost a complete reversal of fortunes. Before the hearings started, only 31 percent of the nation viewed Watergate as a serious matter but, as the hearings and reporting progressed, ultimately 53 percent viewed it as problematic.
The conventional wisdom about Trump's approval rating is that they're stubborn and barely budge. That has generally been true. But just like Nixon, if more details of his collusion and obstruction come to light in public hearings and elsewhere, his numbers could easily be depressed even further. Trump doesn't have high enough approval ratings to make the fallout as dramatic as it was for Nixon. But the notion that he couldn't drop below his previous low of 35 percent seems short-sighted; while the reverse proposition—him suddenly breaking through 45 percent—seems fanciful for a president who consistently does absolutely nothing to endear himself to anyone but his base. In fact, 57 percent of voters just told NPR they would definitely vote against Trump in 2020. Trump’s ceiling is real, but where his floor is remains to be seen. And dropping anywhere close to having just a third of the nation's support is very dangerous territory for a politician who has engaged in as much malfeasance as Trump and has few friends on Capitol Hill.
Check out Pew’s more detailed chart of Nixon’s fall from grace.