Most Republicans appear set to dismiss the charges of "incitement of insurrection" against Trump, with all but six of the Senate's 50 GOP senators voting on Tuesday that it was "unconstitutional" to try the 45th president now that he has left office.
But even some Republicans who signalled their intent to exonerate Trump after his supporters fatally stormed the Capitol on 6 January were unable to stop themselves from criticising his lead counsel Castor's opening monologue – which reportedly had Trump himself "basically screaming" at the TV.
While Trump's defence team intended to argue that the impeachment was "unconstitutional" and that Trump's speech was protected by the First Amendment, Castor began his rambling opening statement by admitting the Democrat team's "well done" had led him to quickly rethink his own.
He then launched into a bizarre speech which discussed ancient Rome, the founding fathers and Nebraska – but only mentioned "Trump" five times, at one point to say: "After he's out of office, you go and arrest him."
Trump ally Ted Cruz conceded that while the Democratic legal team's performance – which focused on footage from 6 January, including from Trump's "Save America" rally – was "impressive", he didn't think Trump's lawyers did "the most effective job".
John Cornyn of Texas was more forthcoming, saying Castor “just rambled on and on and on”.
This left some of Trump's staunchest defenders appearing to tie themselves in knots – not least Fox's Sean Hannity.
In his Tuesday show, Hannity insisted that he was "not attacking" or "being critical" of Castor – before immediately describing his performance as "weak", "lacklustre" and "meandering".
The first instance came while speaking to Cruz, with Hannity saying: "I thought it was a little bit of a weak start. I'm not being critical, just a little lacklustre, meandering to me. It needed a little more focus."
Moments later, he told Castor's colleague David Schoen: "I thought it started a little meandering. It was sort of like, a lot of free-associating in the beginning. And I'm not attacking your partner, I don't know him at all."
Viewers were quick to notice his apparent discomfort.
When reality forces itself on you. https://t.co/bKtTt07p4W
However, his fellow Fox presenter Laura Ingraham – another longstanding Trump defender – praised Hannity for his comments to Schoen as she began her own slot, saying: “I’m glad you pressed the Trump lawyer on the first lawyer who presented the case.”
But when Hannity repeated his comments that Castor's argument was "a little meandering, a little free-associative", Ingraham cut in: "It was terrible. I'm sorry, it was.
"You're way too charitable. If you hired that guy in a case that you were paying the bills on, it woulda been like 'I’m sure you’re a nice person, but enough praise toward the Democrats'.”
When Hannity conceded he was "a little nervous" at the start of Castor's defence, Ingraham continued: “Oh my God, how much time could he spend praising Democrats. The whole thing was like a walk down memory lane about how much he loves the Senate. This is like story time at the trial. It was ridiculous."
She added: "Sorry. I'm pretty worked up about given what's at stake for the Constitution and the country."
Meanwhile, Trump's trial continues – with or without Fox's coverage.