I think this is incorrect - almost noone is now denying that it happened. That Trump made investigation of Biden's son a condition of releasing military aide.
This is the statement that Republican senator Lamar Alexander made, with which a large number of his senate colleagues have concurred, as to why he didn't want to extend the impeachment trial:
“I worked with other senators to make sure that we have the right to ask for more documents and witnesses, but there is no need for more evidence to prove something that has already been proven and that does not meet the United States Constitution’s high bar for an impeachable offense,” Alexander wrote. “There is no need for more evidence to prove that the president asked Ukraine to investigate Joe Biden and his son, Hunter; he said this on television on October 3, 2019, and during his July 25, 2019, telephone call with the president of Ukraine. There is no need for more evidence to conclude that the president withheld United States aid, at least in part, to pressure Ukraine to investigate the Bidens; the House managers have proved this with what they call a ‘mountain of overwhelming evidence.’ ”
The argument is not whether or not Trump did it. It's whether that particular quid pro quo was an impeachable offense.
And I suspect the voting will come down on precise party lines when it happens later today, with the possible exceptions of Manchin in West Virginia (a blue senator in a very deep red state) and Mitt Romney (because Utah is bonkers, hates Trump and the Democrats, and he can pretty much get away with what he likes).
On the general issue - I think Trump is winning in November regardless of who the Democrats put up......unless there is a financial/economic shock before then (in which case he's probably toast). Most incumbent presidential votes come down to the economy, and the majority of Americans have been doing pretty well financially over the past four years.
But I hope that Bernie wins the nomination, because at least then we'll have a genuine debate of the big issues. He won't get distracted or rail-roaded, and will talk about policy and some of the real problems America faces - and will force Trump to address those issues as well (or make him look like an ignorant fool.....both are possible). He's too left-wing for middle America, but may at least get a few more Americans to start thinking........