Will lose an immense amount of respect for Sanders should he endorse someone who represents everything he's been fighting against for decades.
So you'd gain respect for him if he blatantly lied instead? Because he's said dozens of times he would support the Democratic nominee.
Have Sanders lie once instead of endorsing a pathological liar? Yeah I'd take it.
Ah, that good old True Leftist principle strikes again. "It's okay, as long as a man does it!"
All politicians lie. In fact, all humans lie. St. Bernard is no exception.