There are good reasons to conclude that Warren would be the better candidate to face Trump in the general election.

Biden is a lot weaker than he seems. A new Marist poll for PBS and NPR, released in mid-September, compared overall approval ratings for the major Democratic candidates. Warren led the field with 75 percent favorable and just 11 percent unfavorable, for a net positive rating of 64 percent. Biden lagged well behind with 22 percent unfavorable and a net positive rating of only 49 percent.

By early October, Warren was leading the Democratic field. Biden’s ground game in the key early states of Iowa and New Hampshire is inferior to Warren’s. Though they are only six years apart in age, Warren often seems a whole generation more youthful.

Should we be concerned that Warren’s far-reaching economic proposals are too expensive or too radical for swing voters? That depends: which swing voters are we talking about? There are basically two kinds up for grabs.