The era of staying out of primaries is over

OPENING THE FLOOD GAETZ -- Earlier this week, freshman Rep. Alexandria Ocasio-Cortez backed a progressive primary challenger who is trying to defeat Ways and Means Chairman Richard Neal (D-Mass.) — a bold move that came days after Speaker Nancy Pelosi made an endorsement shocker of her own, throwing her weight behind Rep. Joe Kennedy's bid to unseat Sen. Ed Markey. And after GOP Conference Chairwoman Liz Cheney initially supported Rep. Thomas Massie's (R-Ky.) Republican opponent, conservative Rep. Matt Gaetz backed the successful GOP challenger to his colleague Rep. Ross Spano (R-Fla.).

These are just the latest examples of how the dam is breaking on playing in primary battles involving incumbents — something long considered taboo on Capitol Hill. And while leaders in both parties have painted their involvement as a special case, young insurgents are using it as a green light to flex their own muscles in contested primaries. "If the establishment is going to start shooting at the outsiders and the pro-Trump elements of our caucus, then the bullets aren't only going to be flying in one direction," Gaetz said.

This is hardly the first time rank-and-file lawmakers have engaged in primaries — although many more are openly doing so this year — but it's now easier than it was a decade ago for them to actually wield influence. And some are predicting the trend is going to continue. "If in fact there's a district that's suffering… we're going to see a lot more members of Congress supporting challengers," said Marie Newman, who knocked off longtime Illinois Democratic Rep. Dan Lipinski earlier this year with the backing of several prominent Democrats.

But things could get messy, and the old guard is privately worried about intraparty warfare. Leadership and the party establishment protect their incumbents, at least in part, because it's not good for morale or team building if members are openly trying to oust each other. "Politics is a team sport. And if your team devolves into this type of fighting, it's really hard to put that back together," said Brendan Buck, a GOP strategist and former Paul Ryan aide. The dispatch from your Huddle host and Heather: https://politi.co/34GdFVZ.

Related read: "Matt Gaetz builds national profile, but says focus is on Trump election," by Roll Call's Lindsey McPherson and Stephanie Akin: https://bit.ly/31zjP8g.