Suddenly, liberal op-ed writers are trashing – even lampooning – Barack Obama as a one-term president (“one and done”). Centrist Democrats up for re-election in 2012 openly worry about inviting a kindred president into their districts, lest the supposed new pariah lose them votes.

Left-wing think tanks, environmentalists and academics vent their anger against Obama for supposedly being too soft on Republicans, and too ready to compromise with right-wingers. But what really caused the left-wing falling-out, less than three years after the hope-and-change crush on Barack Obama?

For now, polls.

Obama’s popularity has plummeted to little more than 40 percent approval. Suddenly, Democrats worry that the public anger could be contagious. It might infect them as well – in the way a sinking George W. Bush hurt congressional Republicans up for re-election in 2006.

Yet the left cannot fairly blame Obama. After all, he rammed through on a strictly partisan vote the century-old liberal dream of a federal takeover of health care – something that Harry Truman, Lyndon Johnson and Bill Clinton never could do. Keynesians never dreamed that a president could actually borrow $5 trillion for domestic spending in less than three years.

The Obama administration even tried to shut down a brand-new Boeing aircraft plant on the shaky argument that the company might thereby be hiring fewer union workers somewhere else. For environmentalists, Obama kept oil producers out of new fields in Alaska, the American West, the Gulf and other offshore sites. Hundreds of billions in borrowed federal money went to failed “wind and solar” plants in an effort to jump-start “millions of green jobs.”

The Obama revolution under the radar was even more insidious. Open-borders activists were promised that the government would not bother illegal aliens unless they were wanted for felonies. Never before has the United States joined a foreign government in suing one of its own states – in the fashion that both the Justice Department and Mexico have either filed or joined suits seeking to overturn Arizona’s immigration law.

From January 2009 through 2010, Obama advanced the liberal dream with a passion not seen since the New Deal days of Franklin Roosevelt. He bulldozed all opposition and rammed through most of what he wanted from a Democratic Congress – Obamacare, record borrowing, record spending, hundreds of hard-left presidential appointees and judges.

Far from being namby-pamby, Obama has gone after opponents like no president since Richard Nixon. He urged Hispanics to “punish our enemies.” He called his political opponents “hostage takers.” The affluent were lumped together with the super-rich and derided as “millionaires and billionaires, "corporate jet owners” and “fat cat” bankers. His supporters in unions and the Congressional Black Caucus freely blasted the Tea Party with slurs – with the unspoken assurances that the president’s constant calls for civility certainly did not apply to them.

Critics may lampoon Obama’s use of a teleprompter, but he still uses it to good effect in his near-daily speeches. Obama is a far better megaphone for left-wing policies than was the lackluster Jimmy Carter, the pompous Al Gore or the condescending John Kerry. He easily outshines the wooden Harry Reid and the polarizing Nancy Pelosi. Compared to Obama and his smoothness, an often gaffe-prone Vice President Joe Biden can seem a liability. Obama is as charismatic as “I feel your pain” Bill Clinton – as we saw in 2008, when Obama destroyed the primary challenge of Hillary Clinton.

So the left cannot really complain either that Obama betrayed the cause or proved particularly inept in advancing it. Instead, what Obama’s supporters are mad about is that the public is boiling over chronic 9 percent unemployment, a comatose housing market, escalating food and fuel prices, near nonexistent economic growth, a gyrating stock market, record deficits, $16 trillion in aggregate debt, and a historic credit downgrading. And voters are not just mad, but blaming these hard times on the liberal Obama agenda of more regulations, more federal spending, more borrowing, more talk of taxes, and more “stimulus” programs.

A mostly moderate-to-conservative public has concluded that it does not like the new liberal agenda. After three years, it believes that the big government/big borrowing medicine made the inherited illness far worse. Voters may or may not like Obama, but they surely do not like what he is still trying to do.

In response, the left needs a sacrificial lamb. So it has nonsensically turned with a fury on Obama as if he were culpable for getting through the left’s own agenda. If Democrats do not blame the public’s anger on their once-beloved messenger, then they are left only with their message itself. And that is something they simply cannot accept.

© 2011 TRIBUNE MEDIA SERVICES, INC.