Andrew McCarthy of National Review Online warns that it’s not possible to guarantee a particular outcome from the presidential impeachment battle.
[N]obody knows for sure how impeachment proceedings will go. Of course, we have heard again and again over the last five weeks (or is it three years?) that it is inconceivable Donald Trump could ever be ousted from the presidency. His firewall against being stripped of power (and, his supporters hoped, against the House’s even bothering to impeach him in the first place) has always been Republican control of the Senate, where a two-thirds supermajority is required to remove a president. Assuming all Democrats voted to convict on any article of impeachment, Trump would be assured of acquittal if he lost no more than 20 Republicans.
Notice, though, that there’s always been a caveat to such confident predictions: As long as there is nothing other than what we already know about. …
… The point is that life around Hurricane Donald changes fast. Are you really so sure there’s nothing else out there? After three years in which the script seems to flip every three hours or so?
Impeachment is the unknown. Once the unwieldy, rarely used machinery is up and running, no one knows for sure how things will shake out. Richard Nixon won what was then the biggest landslide election in modern American history, yet after less than two years of impeachment hearings, he was too unpopular to survive. Bill Clinton’s trysts with a White House intern were so appalling that, if acknowledged early on, he probably wouldn’t have survived. Months of impeachment sniping ended up working to his advantage.