(The Times has been crying "extremist GOP" for years, if not decades - an October 2003 story  by James Traub for the Sunday Magazine ranted that "Today's Republican Party is arguably the most extreme - the furthest from the center - of any governing majority in the nation's history.")
From Monday's editorial:
Six months after voters sent Republicans in large numbers to Congress and many statehouses, it is possible to see the full landscape of destruction that their policies would cause - much of which has already begun. If it was not clear before, it is obvious now that the party is fully engaged in a project to dismantle the foundations of the New Deal and the Great Society, and to liberate business and the rich from the inconveniences of oversight and taxes.
At first it seemed that only a few freshmen and noisy followers of the Tea Party would support the new extremism. But on Friday, nearly unanimous House Republicans showed just how far their mainstream has been dragged to the right. They approved on strict party lines the most regressive social legislation in many decades, embodied in a blueprint by the budget chairman, Paul Ryan. The vote, from which only four Republicans (and all Democrats) dissented, would have been unimaginable just eight years ago to a Republican Party that added a prescription drug benefit to Medicare.