They really want Pence as the President ?
No. If they remove Trump from office, Pence or another candidate would be easier to beat in 2020. Or so they think.
If, as is almost certain, the Senate refuses to remove him from office, they get another few weeks of free TV time to lie to the low information voters, and maybe convince some voters to vote for their cndidate by libelling Trump some more.
One wild card: If there realy is a trial in the Senate, Biden will be pretty much dirtied up and will lose some votes. I don't think Crazy Bernie, Pocahontas, or the South Bend Butt Boy could beat Trump because the "moderate" democratsnwon't support them with much enthusiasm.