Smart move. Not terribly courageous, but politically smart nonetheless. Despite calls from progressives — and frantic contacts from Bernie Sanders’ campaign — Elizabeth Warren won’t endorse the man whose ideological alignment comes closest to her own. Nor will Warren throw her weight behind the man who has emerged as the frontrunner, the New York Times reported today:

Senator Elizabeth Warren, whose endorsement became highly coveted in the Democratic presidential race after she dropped out last week, is unlikely to endorse her ideological ally Senator Bernie Sanders, according to several people close to her, even though Mr. Sanders is looking for political lifelines as he struggles against former Vice President Joseph R. Biden Jr.

Ms. Warren is expected to withhold her endorsement from Mr. Sanders as well as Mr. Biden at this point, choosing to let the primary play out rather than seek to change its course, according to several people familiar with Ms. Warren’s thinking who spoke on the condition of anonymity to discuss her considerations. …

Ms. Warren has spoken to Mr. Biden once since Super Tuesday but multiple times to Mr. Sanders, as she and her team have fielded overtures from Sanders supporters seeking to coax her to his aid.

Some of the Vermont senator’s prominent online supporters have clamored for Ms. Warren to get behind his campaign, given how closely the two politicians are aligned on policy matters.

They can “clamor” all they want, but there’s no point in joining a bandwagon whose wheels are presently coming off. What would Warren gain from endorsing Sanders at this point? Her party’s establishment wants to get this fight over with so that they can focus on beating Donald Trump with Joe Biden, which a Bernie endorsement would only delay a little longer. It wouldn’t expand her own contacts with voters, and could actively damage prospects for partnerships with other legislators and donors for her next Senate election.

On the other hand, Warren doesn’t stand to gain much from endorsing Biden either. She might disappoint progressives for keeping Bernie at arms’ length, but a Biden endorsement at this point would contradict almost everything she represented in this cycle. Warren’s not going to be Biden’s running mate — she’s proven too unlikeable to be of use in that role — so there’s no real reason to embrace him while Bernie’s still competing.

One has to wonder, though, whether Warren’s making this precise calculation, or just running on her gut disgust with the Bernie Bros:

Warren claimed that so-called Bernie Bros, as Sanders’ staunchest supporters have come to be known, posted the home addresses and phone numbers of numerous women of color who worked for or ran groups that had either endorsed her or not endorsed Sanders.

The move, she said, led to an “onslaught of online threats.”

The Massachusetts progressive was adamant that the candidate himself bore some responsibility for his supporters, who were acting in an effort to support Sanders.

“I wanna say this for all of the candidates, back when there were lots of us, we are responsible for the people who claim to be our supporters and do really threatening, ugly, dangerous things,” she remarked.

Go figure that Warren doesn’t want to spend the next couple of weeks hanging out with that group.

This will likely change after Sunday’s debate, or Tuesday’s round of primaries. If Sanders finds a way to do a lot of damage to Biden in the debate and start winning these contests, Warren might line up with Sanders in an attempt to keep the race open for progressives a while longer. If, however, Sanders doesn’t move the needle, Warren will probably join the calls to close up the fight sooner rather than later.