"Heritage Action", a conservative policy organisation, has a scorecard for conservative voting. Ted Cruz is 97%. Bernie Sanders is 20%. The average Democrat Senator is at 8%. Senator Tim Kaine? 2%.
www.heritageactionscorecard.com/...
I’m certainly not going to suggest this is the ONLY method to assess a candidate's progressiveness, but I think it’s a very interesting metric to consider. Perhaps Tim Kaine offers a progressive ideology in a moderate centrist image. if so that could be a win / win for progressives and Clinton’s electability with the general voting public.