Now that Joe Biden has entered the 2020 presidential contest — ending the least suspenseful build-up to a campaign launch in recent memory — we might take this opportunity to look at how his candidacy will serve as a lightening rod for the Democratic electorate as it begins the process of sorting out how to run against Donald Trump. Biden is not someone you would normally think of as a divisive figure. Loquacious and avuncular, he can be easy to like. Many years ago, I was working with his staff to arrange for him to speak on my campus when one afternoon my office phone rang. “Professor!,” said the loud, engaging voice on the other end. “It’s Joe Biden! How are you?” Senators do not make their own speaking arrangements, or spend time chatting with strangers they don’t plan to ask for money. I found the exchange endearing.

Yet as we begin a campaign season that will determine how much democracy will be left after the Trump interregnum, Biden’s candidacy serves as the fault line between past and future with Democrats left to decide which of these two directions best informs the present. In the lead-up to Biden’s announcement, I have engaged with people whose political acumen I deeply respect who fall passionately and unambiguously on both sides of the Biden divide — those who believe he is the only realistic vehicle for saving the republic and those who believe he is a anachronism who cannot lead in the twenty-first century.

The arguments mirror each other and are based in a competing set of claims that turn on a single, critical and unknowable question: is the emerging electorate large enough, strong enough and mobilized enough to take power in 2020?

I will try to do justice to both arguments. The Pro-Joe camp makes the following claims:

The Hell-No-Not-Joe camp responds as follows:

You may notice a generational and gender divide running through these arguments, along with a sincere difference of opinion about the substantive direction the Democratic Party should take. Although I am neither the right age or gender I do side with the anti-Biden camp on the substantive argument, and despite my personal affection for Biden feel he neither appreciates nor can rise to this very large moment. I also believe there are few truly undecided voters — people have largely staked out their ground — so motivation to vote and protecting the vote will be more important than persuasion. I am ready to assert that the emerging electorate will be large enough next year to carry an election if they are sufficiently engaged and enfranchised. But I recognize that, like those on the other side of the argument, it is only an assertion. Either side could be wrong.

So there is a lot here to sort out, and early polling says that Democrats have a long way to go before they do. Well over half the respondents in an ABC News-Washington Post survey released last Sunday did not support any candidate. Biden topped the poll with a stunning 13% of the vote (Sanders was second with 9%). Add leaners and he made it all the way up to 30% (Sanders was at 20%), making Biden only a slightly more formidable early frontrunner than Jeb Bush was in 2016 — strong enough that he doesn’t have to put an exclamation point after his first name to remind people to get excited about him, but disconcerting for somebody everyone knows. Surveys reflecting his post-announcement polling “bump” show little more than temporary consolidation of this soft support, with Democratic voters divided between prioritizing a candidate who backs issues they care about and prioritizing a candidate who they believe can defeat Trump. This means that if Biden is going to get the nomination he is going to have to earn it by expanding his appeal. At this very early stage, the future direction of the Democratic Party and quite possibly the republic remains open for debate.