The news was not unexpected — Ayanna Pressley fans have been talking her up for this seat for years — but that it actually happened has stunned the political world. City Councillor Pressley, now in her fifth term, will challenge Congressman Michael Capuano in the Democratic primary.

Can she win it ? can she even make a fight of it ? I’m not confident that she can, but if she does make a fight of it, only one political situation gives her the fuel : identity politics.

Pressley is a woman of color. Mike Capuano is an “old white guy.” That’s your campaign in a nutshell.

This should not be. Campaigns for public office should be about policy and character, effectiveness and, yes, incumbency, because long incumbency gives the office holder major influence. In this situation, both candidates have high character, both are justifiably well liked, and both advocate more or less the same policies, though with different priorities. (Capuano emphasizes labor issues, Pressley new-city business matters.) I doubt that the matter of priority has any bearing on the campaign; but who the two candidates are, matters a lot.

It is NOT just a matter of gender and skin color. What’s really happening here is a major incidence of the Democratic party’s increasing split between those who, on the one hand, prefer to accommodate and work bipartisan, and those who on the other hand, reject all compromises. We saw it in the recent government shut-down, where the no-compromise “base” condemned the 34 Democrats who voted to end the shut-down.

The angry radicalism of Mr. Trump has radicalized both political parties. It has all but killed the Republican party and has now split the opposition party. Anger begets anger, and one is tempted to view Mr. Trump’s angry polarization as a bait to trap the Democratic party into responding to him in kind. So much for “when they go low, we go high.” Yet the Democratic party split has other causes than Mr. Trump’s work. The so-called “meToo” movement has split the party badly, never more so than the political assassination of Senator Al Franken by women Senators led by Kirsten Gillibrand. Opponents of that assassination — and I was one such — decried his being bullied out of The Senate without any sort of due process or ethics hearings. Supporters seem to want accusation to be judge, jury, and executioner and to apply the same level of radicalism to all manner of policy and to the Democratic party as a whole. Thus the primary challenge to Capuano, so identical to primary challenges these past four elections against Republicans in Congress.

In the 7th Congressional District, the break down favors Capuano, but not by much. Pressley’s likely support from radicalized white women — who want Capuano types out,  — and voters of color, who support Pressley for her own accomplishments (which are significant), gives her an upper hand in the Boston wards south of the Harbor (but not in Readville and Fairmount Hill), the District’s Cambridge portion, and a strong showing in Milton and Randolph; whereas Capuano can count on Charlestown, most of East Boston, his home town of Somerville, the Matignon area of Cambridge, Everett, and Chelsea. I suspect that Capuano will do worse in Somerville than he should — the City is now home to many young radicals — but better in Randolph and Chelsea than Pressley would like. The decision may be made in Brighton’s Ward 22, a part of Boston much more traditional in its voting than people realize, with long and broad ties to the accommodationist practice of politics and policy. Much will depend upon turnout, in a primary that Secretary Galvin has brutally scheduled the day after Labor Day.

—- Mike Freedberg / Here and Sphere