I was just thinking about this. Knowing that he's going to be acquitted by the Senate, and that he might benefit, electorally speaking, from claiming that he was exonerated, it didn't make much sense to me.
I think the Democrats are already pretty confident of winning the presidency - they lost by only 50k votes (combined margin in Pennsylvania and Michigan, which together would have been enough to flip the Electoral College) and they can expect pretty much anyone they have currently in the race to outperform Clinton. They aren't really trying to remove the president, or to weaken him in the next election.
My guess is that this is actually a move to improve their chances of retaking the Senate. If Trump loses his reelection bid as they predict, it's likely that his supporters at trial will also take a hit at the polls, so the Democrats want to force the Republican senators to link their fates to the president's. They're specifically targetting seats in Maine, Colorado, North Carolina, and Iowa. With those four seats and the vice presidency, they would control the Senate even while losing Alabama.
Even if they only pick up a couple, it would put the Republicans in a tough situation in 2022, when they must defend swing states of Pennsylvania, Wisconsin, Florida, Iowa, North Carolina, Ohio, and Arizona. Opposing Obama helped the Republicans gain more seats, but now as the ones they won in 2014 and 2016 come back up for reelection, they mightn't have enough support anymore to retain them.
@khird So the first part.. when you say "it didnt make much sense to me".. . depends on your goal. If your goal is to have a vote on the issue and come to a democratic conclusion then it makes a lot of sense. Winning shouldnt be your goal, arriving at truth should be. Seeing as they couldnt even get democrat support for the impeachment, let alone bipartisan support, their case would appear rather weak, and they know it.
As for the democrats winning presidency, I'm not so sure. Yes they came close to winning the last election, but that isnt really a measure of their chance of winning this one. Trumps Approval rating just before impeachment was above that of even Obama's. So knowing that it seems clear to me the impeachment was a desperate act to change that. Now that the they dropped the ball on the impeachment I dont think they did themselves any favors really.
I dunno it looks to me like the democrats are a sinking ship and just grasping at straws to win at this point. In the long run i think it will hur tthem more than help.