Bernie Sanders goes for the campaign kill

His campaign events in Massachusetts show disrespect for Elizabeth Warren.

A Bernie Sanders win in Massachusetts would come at the cost of Elizabeth Warren's political dignity. He spoke on Boston Common on Saturday.Craig F. Walker/Globe Staff

Let’s call Bernie Sanders latest campaign move exactly what it is:

Shabby, Bernie, shabby.

As he pursues the nomination of a party he hasn’t even deigned to join over the long term, Sanders is coming to Elizabeth Warren’s home state for two pre-Super Tuesday stops — Springfield on Friday, Boston on Saturday — in the hope of dealing her a campaign-ending defeat. He’ll be in Minnesota on Monday, with the same goal regarding Amy Klobuchar.

Warren’s campaign is already facing tough times, while Sanders is ascendent among the progressive voters the two are vying for. Leading in both California and Texas, he is expected to rack up some big victories on Super Tuesday, while Warren will likely be left to try to put a shine on more discouraging results.

But that’s just another reason why his raid behind her political lines is an affront to his Senate colleague, supposed friend, and left-wing ally. Any advantage he gains would come at the cost of her dignity.

After all, it’s not just that a loss in her home state would likely mark the end of Warren’s presidential hopes. It would also visit a major humiliation upon her in the process.

Sanders, however, is perfectly willing to do that to a fellow progressive senator, one who has been so gentle in her campaign criticism of him that their left-lane rivalry has barely risen to the level of a political pillow fight. That despite the endless targets of opportunity his record presents.

“It is very disrespectful and disappointing that after so many years of collaboration, he would come in to try to embarrass Elizabeth in her own state,” says Phil Johnston, former chairman of the state Democratic Party and a Warren supporter.

It’s also revealing.

Now, as everyone knows, politics ain’t beanbag. And there certainly could be opportunity in audacity for Sanders. One poll now has him ahead of Warren in Massachusetts, while another shows the race a virtual tie.

But there’s also a very real risk of overreach — and of a backlash. If she plays it skillfully, Warren can rally her state to her side. Her surrogates, meanwhile, have an opportunity to shine an illuminating light on Sanders.

After all, there is something exceedingly off-putting about unbridled ambition.