I think the weakest article is 2. Its going to go down. Article 1 will be defeated along party lines.
Yes, even if a Republican Senator votes to hear witnesses, or believes Trump asked for the quid pro quo, that does NOT mean they are voting to convict.
Actually, I wouldnt be surprised if the President did link the aid with looking into Biden corruption. I see nothing wrong with that, even if some part of the reason was to damage Joe Biden, i.e., influence the election.
So what.
Look at what they have put President Trump through for four years - a politically motivated attempt to get him thrown out of office on false charges, enlisting the help of anti-Trump Obama holdovers in the bureaucracy - an abuse of power thousands of times worse than anything Trump ever did.
The Democrats are total hypocrites, contradicting everything they said 21 years ago when the shoe was on the other foot - and ALL those Senators know it.
Even Trump-hating senators like Mitt Romney will vote to acquit rather than get their hands dirty with this tainted Democrat impeachment. I think a fair amount of Democrats will vote to acquit as well.