Joe Biden is enduring in the 2020 Democratic Primary.
The UV Center for politics says Biden's stay at the top is "reminiscent of Mitt Romney’s endurance in the 2012 GOP race." Romney and Biden benefit from splintered opposition and being the best fit for a significant bloc of party regulars.
Romney beat a weak GOP field in 2012 and lost of Barack Obama.
UV said the Democratic field is full of weak candidates with low electability.