Yeah, the Republicans don’t care anything about that. No would anything Trump say do any more than embarass them when they vote to acquit. They are not impartial jurors and never will be and never intend to be. They will be partisan then accuse the Dems of being partisan to either a) try to gain the high ground or b) excuse their own partisanship.
However, Trump may choose to testify anyway because he doesn’t care about embarassing Republicans and he likes the sound of his own voice. The point of the impeachment is to solidify the public against Trump and all the Rs who vote to acquit him when he clearly did as charged, and what he did was the worst a president can do while failing to succeed in those efforts.
While his duties as president are over, would his newfound “concern about distraction” from MULTIPLE ONGOING LAWSUITS be a legitimate cause for Trump to pass up on the invitation?
The guy who wimped out of testifying for Mueller -preferring to lie by written report instead - is not going to voluntarily testify. Especially as he wouldn’t be able to control the questions and would be stopped if he tried to raise false accusations of election fraud.
Invoking the fifth, while his best bet, would seem pretty cowardly, I would think, to his rabid fellow coup-plotters. Trump knows when his bullshit fails, and it would fail in a court of law where he’s sworn to tell the truth.
Senate trial is not a criminal trial, it is more akin to a civil trial for due process purposes, so the House can seek to call the defendant here. If defendant’s testimony, however, would tend to incriminate him, he can assert his 5th Amendment right to refuse.