Remember when GOP Sen. Cory Gardner of Colorado got buttonholed by a couple of local journalists asking him whether he thought, hypothetically speaking, it's okay for a president to ask a foreign leader to investigate a political rival? Gardner gave every dodge known to man in the process of creating some riveting video in which he never actually answered the question. And he never answered it because the only reasonable response would have boxed him into implicating Donald Trump.
This is exactly why Senate Republicans are hoping to rush through a show trial, in as few as a couple of weeks, that includes zero witnesses. Trump is guilty, and a lengthy trial with witnesses will only serve to reinforce just how guilty he is and highlight the GOP's complicity in failing to protect the Constitution and hold Trump to account.
In fact, even as Trump has repeatedly promised his cultists that the Senate trial would include witnesses like Hunter Biden, House Intelligence Committee chair Adam Schiff, and the whistleblower, Senate Majority Leader Mitch McConnell has told his caucus that a lengthy, witness-laden trial would amount to "mutually assured destruction." But that's a carefully chosen and misleading phrase on McConnell's part. Mutually assured destruction implies that the damage done on both sides would be so catastrophic that it would be a lose-lose draw. That's not actually true: The hurt would be much worse on the GOP side because whatever harm might come to former Vice President Joe Biden and Democrats, the facts are on their side.
Dragging the Bidens through the mud in service of a ridiculous conspiracy theory that only Fox News viewers believe has far more downsides for the Senate Republican caucus than upsides, particularly because Republicans will be playing defense in more states than Democrats in 2020. While Democratic Sen. Doug Jones of Alabama is facing a tough reelection battle, Republicans will have their hands full trying to protect a handful of senators including Gardner, along with Martha McSally in Arizona and Susan Collins in Maine, among others.
The strategic disadvantage for Republicans of a longer trial with witnesses is exactly why Democratic Senate Minority Leader Chuck Schumer has begun pushing to hear from witnesses close to Trump, such as acting White House chief of staff Mick Mulvaney and former national security adviser John Bolton.
Multiple polls have shown that the vast majority of Americans (on the order of 70%) think that what Trump did regarding Ukraine was "wrong"; multiple other polls have found that a majority of those voters believe Trump's offenses are impeachable (53% in Civiqs) even if some of those same voters don't support impeachment. The last thing Republicans need—not to mention Trump—is to spend five to seven weeks reminding voters of just how glaringly guilty Trump is and how eager he was to sell out the country for his own personal gain.
Even Trump himself could end up more vulnerable to defeat in 2020 following a lengthy Senate trial. Indeed, the December Civiqs poll found that of the 44% of respondents who currently support Trump for reelection, only 30% said nothing could change their minds between now and next November, while 14% said they are still open to changing their minds (that compares to 48% of voters who both oppose Trump and said nothing could change their minds). That means Trump's support is still somewhat fluid among a decent portion of people who currently plan on voting for him. Hearing incriminating testimony from someone like Bolton certainly won't improve Trump’s prospects any.
In the meantime, every Senate Republican should have to answer the question of whether, hypothetically speaking, they think it’s okay for a president to solicit help from a foreign government in order to win reelection.