The more progressive democratic candidate has a bigger lead? Wow haven't heard of that happening before. 
Lol. But seriously, what is this idea that Perriello is more electable than Northam based on anyway? That he has more appeal in rural areas than Northam? I highly doubt that'll be the case on election day, and I also doubt that he would do better than Northam in the general election, despite what all of these polls are saying now.
If I were a Democrat, I'd probably root for Northam here. He's the safe choice IMO.
Northam would be a great candidate to have in Alabama with Moore as the nominee, or Louisiana with Duke. But that's not what's at play in Virginia. If Democrats can afford to be dynamic, then we should be.
We want Perriello because we trust him more to actually fight for and implement the policies that we want. Irrespective of whether or not he's more "electable" (he is) he'll be a more effective implementer of left and liberal ideas.
But if he kept even his 2010 margin in the VA-5 and performed like a normal Democrat in NOVA, Richmond &c that would be pretty neat.
Virginia doesn't go for populists, whether they be on the left or the right, as evident by Trump's 5% loss in the state. They go for technocrats and establishment candidates, as evidenced by Clinton's, Northam's, and Gillespie's victories.
