(CNN) -- Damn those extreme Republicans. President Obama and White House press secretary Jay Carney have found Republicans guilty of extortion and blackmail. Joe Biden, per a report in Politico, once christened Republicans as terrorists.
Liberals have led a media assault, calling the GOP anarchists, jihadists, "gun to head" hostage takers, and the political equivalent of the Taliban. White House advisor Dan Pfeiffer has likened Republicans to suicide bombers "with a bomb strapped to their chest."
What could be more extreme?
The Democratic Party.
True, the Ted Cruz wing in the House of Representatives is relentless, uncompromising and unmoved by practicality. As we all know, there are perhaps 40 or so "bullet-proof Republicans" in the House, in safe GOP districts, invulnerable except to Kryptonite. They fear a fellow Republican getting to their right in a primary more than a long-shot Democratic opponent who would paint their district blue in a general election.
No doubt, the GOP is a party divided, but there are a lot of Democrats in safe districts, too. Why don't they fear a fellow Democrat getting to their left in a primary? Why aren't the Democrats a party divided between a centrist mainstream and a more extreme, radicalized left?
Let us count the reasons: Barack Obama has taken the Democratic Party left of Clinton. He left blue-dog, centrist Democrats to be punished for his sins and they were wiped out in the GOP's 2010 Congressional landslide. All the while, the Internet has empowered and organized the party's remaining and most extreme elements. The Democratic Party can't go left. It is left, in entirety. They already occupy America's left fringe.
Bill Clinton's New Democrats are dead. This is not Hillary Clinton's Democratic Party. Today's Democratic Party belongs to Elizabeth Warren. It is the party that just nominated a Sandinista trainee who returned from Nicaragua with "a vision of unfettered leftist government" for mayor of New York City, according to the New York Times.
And today's Democrats think this is a good thing.
They dream audaciously, as Ruy Teixeira wrote in the Atlantic, of a new "Emerging Democratic Majority." As Peter Beinart noted in a Daily Beast piece, "The Rise of the New New Left," "Bill de Blasio's win in New York's Democratic primary isn't a local story. It's part of a vast shift that could upend three decades of American political thinking."
The Democratic Party is now animated by the "mobilized left," Beinart writes, emboldened by Internet activism. Their cause was galvanized by President Obama's seemingly impossible re-election.
Once, Obama may have campaigned as a centrist, but that was long ago. He has since governed as an old school economic liberal from the '60s. As Fred Thompson has noted, Barack Obama has been "George McGovern without the experience." Obama's answer to every economic challenge has been top-down. Our governing class knows best, he believes, especially since Washington's elite now includes him.
If the world has changed in eight decades, our President hasn't noticed. His view of government is cast from the bronze of Franklin Roosevelt and the '30s. He puts our big, dumb, inflexible public sector at the top of American life, to mandate redistribution and prosperity.
At every opportunity, he has grown the public sector's archaic program-and-policy factory. This empty presidency tries only to cure too much old government with even more of it. Though little of what he has tried has worked, it has not seemed to deter his party. It hasn't deterred him.
His government doesn't govern education: The U.S. educational system barely edges out nations such as Slovakia, in international rankings. His government doesn't govern retirement: Our public-sector retirement system is akin to an unsustainable Ponzi scheme. His government doesn't govern health care: The Affordable Care Act is making health care more unaffordable for many seniors. His old government doesn't govern our economy: A record high 89 million Americans don't participate in the workforce and 300,000 more dropped out this August. Barack Obama is building the largest public sector since World War II and, yet, our government governs nothing.
Still, an intellectually exhausted Democratic Party proposes nothing new. If at first you don't succeed, keep trying until you are $20 trillion in debt and failure litters your streets.
The rollout of the Obamacare website is but another symptom of an old, hierarchical bureaucracy incapable of keeping pace with the complexities of a modern, adaptive America. Healthcare.gov is the best old Washington can do, not the worst.
While our world transforms itself through revolutions in energy, technology and communication, the ideologists of the left stagnate. Barack Obama's Democratic Party is intellectually exhausted. Their old Democratic Party has nothing up its sleeves but more of the same.
How our young President could only offer such dated ideas will be studied for decades. For now, we can mark candidate Obama's transformation from agent of hope and change to defender of liberal calcification as one of the great sleight-of-hand tricks in political history.
With any luck, he will be the last President who tried to teach our dinosauric public sector to dance to the music of a new and adaptive era. Others, beyond Obama, will not expand but instead transform what we now pretend "governs" us. As for his legacy, today's tweeters and texters will remember Barack Obama as the last President of the Industrial Age and once he is gone, there will be no cover for his party's intellectual barrenness.
Obama will leave a Democratic Party epitomized by ancient ideas, radically positioned left of our political center. The political trouble Barack Obama inherited from George W. Bush is nothing compared to what Obama has teed up for a future contender such as Hillary Clinton.
Our former secretary of state has had no choice but to campaign for president earlier than she would have chosen. Clinton can see that this radicalized Democratic Party could easily leave her behind and find another champion. It did so before, to her distress, in 2008.
No other member of the old Democratic elite can possibly hold its left-sliding legions together, yet Hillary Clinton has only one credential that appeals to her party: She could be our first female president. Elizabeth Warren's growing followers, more in tune with today's radicalized, populist Democrats, are likely to find that distinction unimpressive. If Clinton's rationale begins to fray, all hands on deck: The Democratic Party's 2016 nomination process is going to look like the casting call for "One-Flew-Over-The Cuckoo's Nest."
Howard Dean may have screamed his way past the Democratic nomination in 2004, but the revolution he started has borne fruit. The 2016 nomination battle may be a fight between Elizabeth Warren, Governors Martin O'Malley and Deval Patrick, an unpolished pack of ideological duds and even a reinvigorated Dean, all vying to out-crazy each other and take the Democratic Party over a precipice. They'll make the troupe that sought the 2012 GOP nomination look like the committee awarding the Nobel Prize for Physics.
Which party is more extreme?
A Republican Party divided between 180 mainstream House members and 40 Ted Cruz mini-me's? Or a Democratic Party united to preserve our fossilized, ineffective public sector?
A Republican Party advocating a path to fresh, natural, economic growth? Or a Democratic Party offering young voters the outdated economics of conformity, artificially imposed by Washington's elites?
A Republican Party being driven to offer change? Or a Democratic Party united against it?
Entrepreneurs, start printing tie-died shirts now. They will be hot sellers at the next Democratic Convention. Both sides are in for an interesting ride, but for Democrats, it's going to be an extreme 2016.
The opinions expressed in this commentary are solely those of Alex Castellanos.