The attack by the Senate Conservatives Fund underscores how much and how fast the GOP is changing and serves as an opening salvo in what’s likely to be an ugly primary battle next year…

“Senate RINOs are calling it quits!” the group exulted in an email last week asking for money…

“This is the beginning. It’s starting really early, it’s crazy,” said Brian Darling, a GOP strategist and former Senate aide. “We’re going to see a battle between the establishment and the conservative wing of the party and that’s playing out with the Senate Conservatives Fund and many of the more establishment groups that will be backing up incumbents no matter what.”

Darling said the definition of “conservative” is shifting to become more aligned with the issues Trump championed while in office. But he also noted there have always been factions in the conservative movement, with free-trade and pro-business conservatives often in their own camp and libertarians and cultural conservatives in other niches.