There's strong dissatisfaction with both parties, so I wouldn't put too much credence in polling numbers. As we saw with Trump's victory, candidates who are, or claim to be, political outsiders are looked upon more favorably than anyone from the establishment. Look at Oprah's innuendo at running for President in 2020 and the resulting brouhaha that it caused as the most recent example of this phenomenon. The Democrats are still in damage control mode. YMMV.