Edit: And btw, the lastest polls I believe, are showing that support among the voters for impeachment is actually decreasing, probably because the Republicans are very effectively muddying the waters about what really happened, and ruthlessly attaching the witnesses at the hearing.
Everything changes when the House presents their case to the Senate. The rules of engagement are very different. The GOP can't play their usual games. I figure Roberts doesn't want to be the guy who let it turn into a circus when he has the power to prevent it, which he largely will. The case is utterly damning & there's nothing to be said to justify Trump's actions at all. The GOP will almost certainly let him off the hook but they'll have to expose themselves as craven liars & sycophants to do it. Trump constantly changing his story won't make it easy for them, either.