Sander’s vulnerabilities, Chait writes,

are enormous and untested. No party nomination, with the possible exception of Barry Goldwater in 1964, has put forth a presidential nominee with the level of downside risk exposure as a Sanders-led ticket would bring.

Chait bolstered his critique of those arguing for full-throated support of the most liberal policies by citing the success of moderates and the defeat of more radical candidates in flipping seats from Republican to Democrat in the 2018 congressional elections.

The recruitment of moderates by the Democratic Congressional Campaign Committee, Chait writes,

was a good strategy to win the House. Democrats flipped 40 seats. Tellingly, while progressives managed to nominate several candidates in red districts — Kara Eastman in Nebraska, Richard Ojeda in West Virginia, and many others — any one of whose victory they would have cited as proof that left-wing candidates can win Trump districts, not a single one of them prevailed in November. Our Revolution went 0—22, Justice Democrats went 0—16, and Brand New Congress went 0—6. The failed technocratic 26-year-old bourgeoisie shills who were doing it wrong somehow accounted for 100 percent of the party’s House gains.

Sanders’s ascendancy in the nomination fight places the Democratic Party in a double bind. Not only is he potentially a dangerously weak general election candidate but, if an Anybody-But-Bernie movement materializes and successfully defeats him at the convention, Sanders supporters — more than backers of any other major candidates — are likely to bolt on Election Day and vote for either a third-party candidate or even Trump (as many Sanders supporters did in 2016), or sit out the contest altogether. In 2016, more than 7 million votes were cast for third-party candidates, more than enough to have given the election to Hillary Clinton.

A January 22-23 Emerson College survey asked Democratic primary voters “will you vote for the Democratic nominee even if it is not your candidate?” 87 percent of Joe Biden supporters said yes, as did 90 percent of those backing Elizabeth Warren and 86 percent of those aligned with Pete Buttigieg. 53 percent of Sanders supporters said yes, 16 percent said no, and 31 percent said they were undecided.

If that were not enough, Sanders loyalists have been primed by their belief that in 2016 the Democratic National Committee backed Hillary Clinton and view the Democratic establishment with deep suspicion — as evidenced by the displays of anger and resentment toward party leaders at two Sanders events earlier this month in Iowa.

As Michael Tomasky pointed out in a Daily Beast article on Feb, 4, “Iowa Caucuses on the First Day of What’s Poised to be the Ugliest Democratic Primary Fight Ever,” if Sanders becomes the clear front-runner and the party establishment tries to block him, the story line will be

that party establishment corporatist hacks are moving heaven and earth to thwart the pure insurgent, the man of the people. The Sanders army will push it, and so will Trump and Fox News and the Republican Party, because they want Sanders as their opponent. Fox is going to run more “poor Bernie” stories than Jacobin.

There are election analysts, including a number of conservatives, who say that they believe that Sanders would be a credible nominee with a good chance of beating Trump.

In “Don’t Believe Anyone Who Says Bernie Sanders Can’t Win,” David French, who used to write for National Review and is now published in The Dispatch, argued on Jan. 30:

Every single factor that caused reluctant Republicans to hold their noses and vote for Trump will apply to reluctant Democrats. “Binary choice,” they’ll hear. “Judges,” they’ll declare. And, unlike 2016, when a host of people on both sides of the aisle thought there was no way that Hillary Clinton would lose to Donald Trump, not a single member of the Democratic coalition will be complacent. They’ll attack the election with fierce moral urgency.

Now imagine, French continued,

not just a theater full of young, hopeful faces. Imagine stadiums. Imagine that enthusiasm and sense of hope magnified by a mainstream media (especially online) that will march happily behind Bernie’s banner.

French concluded:

We coldhearted analysts and nerds always seem to underestimate the power of victory and hope. If Bernie wins the nomination, he would have triumphed over impossible odds and a small army of scoffers. Just like Trump. If Bernie wins, his core base voters will start to believe that their dreams can be a reality, and they’ll stand with him even if he shoots a man on Fifth Avenue.

Along similar lines, Drew Holden, a Republican consultant, wrote “Of course Bernie Sanders can win,” on Feb. 3 in The Washington Post:

All of these criticisms ignore Sanders’s considerable strengths. He commands a passionate, dedicated and active army of volunteers and small-dollar donors. Sanders’s message, whether you agree with it or not, is consistent and resonates deeply with millions of Americans.

On the liberal side, Matthew Yglesias took on the assignment of making the best case for Bernie Sanders in Vox: “Bernie Sanders can unify Democrats and beat Trump in 2020”:

The Vermont senator is unique in combining an authentic, values-driven political philosophy with a surprisingly pragmatic, veteran-legislator approach to getting things done. This pairing makes him the enthusiastic favorite of non-Republicans who don’t necessarily love the Democratic Party, without genuinely threatening what’s important to partisan Democrats.

Toward the end of his essay, however, Yglesias sounds more skeptical. “At the end of the day, Sanders’s record is not nearly as scary as many establishment Democrats fear. His ‘revolution’ rhetoric doesn’t make sense to me, but he’s been an effective mayor and legislator for a long time,” Yglesias writes, adding “Some of his big ideas are not so hot on the merits, but it’s not worth worrying about them because the political revolution is so unrealistic.”

Most political scientists I contacted this week saw greater disadvantages for the Democratic Party in a Sanders nomination than in the possible selection of other leading candidates.