The following has been excerpted from It’s Even Worse Than It Looks: How the American Constitutional System Collided With the New Politics of Extremism, a new book by congressional scholars Thomas Mann and Norman Ornstein.

Ornstein, who works at the conservative American Enterprise Institute, and Mann, who works at the centrist Brookings Institutions, have laid out a compelling argument that explains how the Republican Party has systemically undermined the capacity of both Congress and broader federal government. You can purchase it here.

It is traditional that those in the American media intent on show- ing their lack of bias frequently report to their viewers and readers that both sides are equally guilty of partisan misbehavior. Journalistic traditions notwithstanding, reality is very different. The center of gravity within the Republican Party has shifted sharply to the right. Its legendary moderate legislators in the House and Senate are virtually extinct. To be sure, a sizable number of the Republicans in Congress are center-right or right-center, rather than right-right. But the insurgent right wing regularly drowns them out. The post-McGovern Democratic Party, while losing the bulk of its conservative Dixiecrat contingent, has retained a more diverse constituency base, and since the Clinton presidency, has hewed to the center-left, with an emphasis on the center, on issues ranging from welfare reform to health policy.

Anyone who has reviewed the voluminous literature on the intellectual and organizational developments within the conservative movement and Republican Party since the 1970s will find that an unremarkable assertion.

The conservative critique of the Great Society social welfare programs and of the regulatory state, the mobilization of the Christian right, and the development of supply-side economics set the policy plate of the modern Republican Party. Over the course of the last three decades, the GOP has become the reflexive champion of lower taxes, reductions in the size and scope of the federal government, deregulation, and the public promotion of a religious and cultural conservatism. The striking changes in the nature of the Republican Party over the past fifty years are especially well documented in the book by political historian Geoffrey Kabaservice, Rule and Ruin: The Downfall of Moderation and the Destruction of the Republican Party, From Eisenhower to the Tea Party. He notes, “movement conservatism finally succeeded in silencing, co-opting, repelling, or expelling nearly every competing strain of Republicanism from the party, to the extent that the terms ‘liberal Republican’ or ‘moderate Republican’ have practically become oxymorons.”

Republican presidents Eisenhower and Nixon and congressional leaders such as Senators Everett Dirksen, Hugh Scott, Howard Baker, and Bob Dole, and Representatives Gerald Ford, John Rhodes, and Bob Michel, pragmatic institutional figures who found ways to work within the system and focused on solving problems, are unimaginable in the present context. President Reagan ushered in the new Republican Party but governed pragmatically. The steps he took in office, as well as those the two Bush presidents took, were so far outside the policy and procedural bounds of the contemporary GOP that none of them could likely win a Republican presidential nomination today without disavowing their own actions.

Reagan was a serial violator of what we could call “Axiom One” for today’s GOP, the no-tax-increase pledge: he followed his tax cuts of 1981 with tax increases in nearly every subsequent year of his presidency. George H. W. Bush agreed to a 1990 deficit-reduction package that included tax increases and budget process reforms, turning back significant congressional Republican opposition (led by Newt Gingrich) along the way. And in more recent years, conservatives turned sharply against George W. Bush’s advocacy of broad immigra- tion reform (a violation of “Axiom Two”), expansion of govern- ment in health care and education (Oops! There goes “Axiom Three”), and steps to deal with the financial meltdown. That legacy, and Barack Obama’s election and extraordinary measures to limit the damage from the financial crisis and deep recession, prompted the formation of a right-wing populist Tea Party movement, which the Republican establishment subsequently embraced.

Chuck Hagel, the former Republican Senator from Nebraska, echoed just these points in an August 2011 interview with the Financial Times. Hagel called his party “irresponsible” and said he was “disgusted” by the antics of the Republicans over the debt ceiling:

The irresponsible actions of my party, the Republican Party over this were astounding. I’d never seen anything like this in my lifetime. . . . I was very disappointed. I was very disgusted in how this played out in Washington, this debt ceiling debate. It was an astounding lack of responsible leadership by many in the Republican Party, and I say that as a Republican. . . . I think the Republican Party is captive to political movements that are very ideological, that are very narrow. I’ve never seen so much intolerance as I see today in American politics.

A veteran Republican congressional staffer, Mike Lofgren, wrote a long and anguished essay/diatribe in 2011 about why he ended his career on the Hill after nearly thirty years. His essay was filled with observations and broadsides like the following:

It should have been evident to clear-eyed observers that the Republican Party is becoming less and less like a traditional political party in a representative democracy and becoming more like an apocalyptic cult, or one of the intensely ideological authoritarian parties of 20th century Europe.

He added,

The only thing that can keep the Senate functioning is collegiality and good faith. During periods of political con- sensus, for instance, the World War II and early post-war eras, the Senate was a “high functioning” institution: filibusters were rare and the body was legislatively productive. Now, one can no more picture the current Senate producing the original Medicare Act than the old Supreme Soviet hav- ing legislated the Bill of Rights.

Far from being a rarity, virtually every bill, every nominee for Senate confirmation and every routine procedural motion is now subject to a Republican filibuster. Under the circumstances, it is no wonder that Washington is grid- locked: legislating has now become war minus the shooting, something one could have observed 80 years ago in the Reichstag of the Weimar Republic. As Hannah Arendt observed, a disciplined minority of totalitarians can use the instruments of democratic government to undermine democracy itself.

And then this observation:

A couple of years ago, a Republican committee staff director told me candidly (and proudly) what the method was to all this obstruction and disruption. Should Republicans succeed in obstructing the Senate from doing its job, it would further lower Congress’s generic favorability rating among the American people. By sabotaging the reputation of an institution of government, the party that is programmatically against government would come out the relative winner.

Lofgren’s frustration may make him more prone to hyperbole than other old-school Republicans — but his observations hit home with many of them, as they do with us.

The GOP’s nearly unanimous pledge, in writing, not to increase taxes under any circumstance is perhaps the best indicator and most consequential component of its ideological thrust. Grover Norquist, president of Americans for Tax Reform and the man who fashioned the “Taxpayer Protection Pledge” to which Republicans pay fealty, has become a legendary power broker in the party. At the same time, its rank-and-file voters endorse the broader strategy the party elites have adopted, eschewing compromise to solve problems and insisting on sticking to principle even if it leads to gridlock.

The Democrats under the presidencies of Clinton and Obama, by contrast, have become the more status-quo oriented, centrist protectors of government, willing to revamp programs and trim retirement and health benefits in order to maintain the government’s central commitments in the face of fiscal pressures and global economic challenges.31 And rank-and-file Democrats (along with self-identified Independents) favor compromise to solve problems over deadlock.

The contrast plays out in a number of striking ways. One simple indicator is this: More than 70 percent of Republicans in the electorate identify themselves as conservative or very conser- vative, while only 40 percent of rank-and-file Democrats call themselves liberal or very liberal. This difference at the level of mass politics is reflected in the ideological composition of the two parties in government. George W. Bush pushed through his signature tax cuts and Iraq war authorization with substantial Democratic support, while unwavering Republican opposition nearly torpedoed Barack Obama’s health-care and financial reform legislation.

When Democrats are in the majority, their greater ideological diversity combined with the unified opposition of Republicans induces the majority party to negotiate within its ranks, producing policies on health reform and climate change that not long ago would have attracted the support of at least a dozen Senate Republicans and thirty to forty House Republicans. Now? Zero in either chamber.

The phenomenon is even clearer when we look at roll call voting averages for parties on the same liberal-conservative dimension over time. Since the late 1970s, Republicans have moved much more sharply in a conservative direction than did Democrats in a liberal direction. And the change that occurred among Democrats was mostly within their Southern contin- gent—the demise of Dixiecrat conservatives and the election of minorities. Democratic representatives outside the South barely moved at all. The 2010 election dramatically increased the conservative tilt of the House Republicans. Nearly 80 percent of the freshmen Republicans in the 112th Congress would have been in the right wing of the party in the 111th Congress.