Is a consistent history of anti-gun policy a new a litmus test for Democratic presidential candidates?

VOX just released an article that illustrates the rapid push to embrace extreme anti-gun policies and the lack of tolerance for Bernie Sanders at one point having a C minus rating from the NRA. One gun control leader says he was stopped dead in his tracks when he read this rare moment of clarity from Senator Sanders:

“If you passed the strongest gun control legislation tomorrow, I don’t think it will have a profound effect on the tragedies we have seen.”

What changed? Bernie Sanders now embraces an all of the above gun-control policy including backpedaling on his defense for his vote against holding gun manufacturers liable for misuse.

Giffords gun-control group and Everytown outspent the NRA in 2018 almost two to one and the big donors like Bloomberg are putting big dollars behind gun-control candidates. The party has also taken a clear step left and is far more emboldened to chip away at the Second Amendment when they gain the power to do so.

Former Virginia Senator Jim Webb had an undeniably strong resume and an A rating from the NRA when he ran for President as a Democrat in 2016. His campaign gained little traction. Will he be the last A-rated Democrat to ever run for President?

What are your thoughts?