For the party of Reagan, his departure was the beginning of a long decline, and it is the absence of a similarly totemic figure, during the past twenty years, that has allowed the current resurgence of extremism. George H. W. Bush repelled right-wingers with his moderate tendencies—not least when, in the face of fiscal calamity, he broke his campaign pledge not to raise taxes. Bill Clinton inspired them to an almost ecstatic series of attacks, and though there remained enough of an older conservative establishment, personified by Senator Bob Dole, to check some of the wildest charges, the new Republican House majority after 1994, pushed by such ideologues as Tom DeLay and Dick Armey, had little interest in maintaining the center. They harassed Clinton, forcing an impeachment even though polls showed that more than sixty per cent of the American people disapproved. George W. Bush seemed at first to have a bit of Reagan’s conservative charisma, but the right wing turned against him for failing to win the war in Iraq, for his moderate position on immigration, and for spending hundreds of millions of federal dollars to combat the financial collapse in 2008. When William F. Buckley died, during the 2008 primary season, it seemed to symbolize the end of a conservative era. David Klinghoffer, a former literary editor at National Review, lamented that “urbane visionaries and builders of institutions” such as Buckley have been replaced by media figures “who make their money by stirring fears and resentments.” Conservatism, Klinghoffer added, “has undergone a shift toward demagoguery and hucksterism,” and is now ruled by those he called “the crazy-cons.”…

Fifty years ago, President Kennedy deplored the far right’s “counsels of fear and suspicion.” Today, Obama’s White House is still struggling to make sense of its enemies. In the absence of forthright leadership, on both the right and the left, the job of standing up to extremists appears to have been left to the electorate. Candidates like O’Donnell may prove too eccentric to prevail, or voters may simply become disillusioned by politicians who campaign on their hatred of government. After the election, mainstream conservatives may well engage in what Richard Viguerie has forecast as “a massive, almost historic battle for the heart and soul of the Republican Party.” (Already, Rove and some leading Bush political operatives, including the former Republican National Committee chairman Ed Gillespie, have been quietly supplanting the battered G.O.P. establishment in the effort to raise funds for this year’s candidates.) But, according to a recent poll, more than seventy per cent of Republicans support the Tea Party, and it seems almost certain that a Republican Party that has unstintingly appeased the far right will enjoy a strong and perhaps smashing victory in the coming midterm elections.

In 1906, early in the Progressive era, the humorist Finley Peter Dunne’s fictional barroom sage, Mr. Dooley, put the social and political tumult of the day into perspective. “Th’ noise ye hear is not th’ first gun iv a revolution,” Dooley remarked. “It’s on’y th’ people iv th’ United States batin’ a carpet.” A century from now, or even a year from now, Americans may say the same about the Tea Party. For the moment, though, it appears that the extreme right wing is on the verge of securing a degree of power over Congress and the Republican Party that is unprecedented in modern American history. For defenders of national cohesion and tempered adversity in our politics, it is an alarming state of affairs.