Until several days ago, former Vice President Joe Biden was the political equivalent of a dead skunk in the middle of the road. (Apologies to Loudon Wainwright III.)

Now, with Biden’s surprising upset victory in the Massachusetts Democratic presidential primary, it’s Sen. Elizabeth Warren who’s roadkill.

That Warren did not win her home state primary was not a total surprise.

Last week, The MassINC Polling Group reported that Vermont Senator Bernie Sanders enjoyed an eight-point lead over Warren. And Sunday, a Boston Globe-Suffolk University poll called the race too close to call — not auspicious for the hometown candidate.

On election day, the situation sufficiently vexed the Warren campaign that it told WGBH News that, yes, there would be watch parties for campaign workers and volunteers, but, no, they were not open to the press.

Not exactly a profile in confidence.

There was good reason for caution. Four years ago, Hillary Clinton managed only a microscopic one percent win over Sanders. The Bernie Brigade subsequently burrowed deep into the local turf.

Days before Super Tuesday, Sanders audaciously brought his campaign onto Warren’s home ground, corralling raucous crowds in Springfield (about 4,500 came) and Boston (the crowd estimate was 13,000).

The inside money was on Sanders dealing a psychic blow to Warren, who had left her home flank unguarded.

What is amazing is that Biden, who hadn’t campaigned in Massachusetts, and who only several days before was polling at nine percent, jumped more than 20 points to score a commanding victory.

Warren may carry the shame, but it is Sanders who wears the real bruises.

If you step away from all of the presidential hoopla, Biden’s Bay State win is not so strange.

Massachusetts is a very blue state with a Republican governor. By national standards some Republicans might consider Charlie Baker almost as red as Bernie Sanders. Massachusetts voters, on the other hand, consider Baker a likable, sensible guy who may not be perfect but who gets the job done with a minimum of fuss.

Sounds a touch like Joe Biden, doesn’t it?

Also remember that while Warren was reelected to the U.S. Senate by a very comfortable margin, Baker was reelected by even more votes.

The Baker-Biden axis is not to be dismissed.

With his dominant South Carolina victory, Biden acquired that most precious and ineffable of electoral qualities, momentum.

That’s not because of his own gosh-darn charms. Rather it’s because Biden became the strongest — or maybe just the safest — alternative to Sanders, a Democratic Socialist who makes the donor class nervous and who the candidate class fear would lose to President Trump in the general election.

All of this leaves Warren in a curious national position.

Because she clearly considers herself more down-to-earth and effective than Sanders, Warren seems to think the national electorate should find her less threatening, less radical. That’s debatable. As Adam Gopnik observed in The New Yorker, “If anything, Elizabeth Warren, in the specificity of her proposals, is to the left of Sanders, but, sadly, not remotely as popular a figure.”

So, it would seem.

As was the case with Biden before South Carolina, Warren has yet to win a single contest — although she is still amassing convention delegates. That is something she has in common with her nemesis Mike Bloomberg, the multi-billionaire former New York City Mayor who is almost winless. He did prevail in America Samoa.

Before the polls closed in Massachusetts, Warren appeared on stage in Michigan where she was campaigning. During her standard stump speech, Warren made it clear that she would not withdraw. She was staying in the race for the White House — until the end.

And with the FiveThirtyEight political forecasting operation placing the odds of a brokered convention at 61 percent, there is a certain sort of logic in that.

But there is a perhaps more potent logic in another proposition: If you can only finish third in your own state, what makes you think you can carry the nation?