The cover of the left-leaning New Republic this week features a cartoon of angry Senate Democrats surrounding an exasperated Barack Obama with the caption: “Why The Democrats Can’t Govern: Look Who’s Killing Obama’s Agenda Now.”

It is true: After he served up a $787 billion stimulus package, a $3.6 trillion budget, restructurings of the bank and auto industries, and a new plan for Afghanistan, some members of the president’s own party have found things they don’t like.

But it would be journalistic malpractice to portray the discontent as a sign of a significant fissure in the Democratic Party.

Truth is, Democrats have not been so in love with a president in my lifetime (though admittedly I was a toddler and not paying close attention when JFK was in the White House). Bill Clinton drew liberal scowls for being a “new Democrat.” Jimmy Carter disheartened the party, and provoked a challenge from Ted Kennedy in the Democratic primaries. Lyndon Johnson angered the doves and the Dixiecrats.

While William Greider mocked Obama’s plan to buy toxic assets on the pages of The Nation, and Code Pink in San Francisco criticized Obama’s plan for Afghanistan, the more typical response came from House Democratic leader Steny Hoyer of Maryland, who praised Obama’s actions as “honest,” “responsible,” “deliberative,” “wise,” “realistic” and “positive” in news releases distributed to reporters in the past week.

Go to the Web pages of MoveOn.org, Americans for Democratic Action, Campaign for America’s Future and People for the American Way — all lions of the liberal movement — and you will find unambiguous support for Obama’s agenda.

Could the love fade? Of course. Democrats are not going to fall apart over negotiable items such as deduction limits for charitable organizations or whether to fix the average minimum tax. But a consequential crack could emerge from questions over Obama’s devotion to the economic status quo. Is Obama too timid to nationalize banks, too reliant on financial insiders like Timothy Geithner to allow institutions like AIG to fail, too concerned about political restraints to spend as freely as Krugman recommends?

An improved economy will render each of these questions moot. A worsening situation would prompt many on the left to wonder what happened to Obama’s promise of change.

For now, despite the news media’s infatuation with pumped-up conflicts, Obama is secure with his base. Many Democrats are idealists. Some are zealous. But most are not fools.

They might want him to nationalize health care, withdraw troops from Iraq more quickly, allow gays to serve in the military and initiate a criminal investigation of Dick Cheney to boot. But they’re not going to let their wish list get in the way of the most liberal agenda of any incoming president since FDR.

For a generation, liberals were told their time was past. George McGovern, Morris Udall and Kennedy couldn’t win. Mario Cuomo wouldn’t run. Reagan captured the hearts — and votes — of the young. Even Clinton admonished his party that the “era of big government is over,” as he embraced GOP proposals for balanced budgets, welfare reform and a stronger defense.

Suddenly liberals have a voice — a beloved voice — telling the country that government is necessary, that investments in social spending make sense, that not all tax increases are bad, that America can be admired around the world. And for now, a majority of the country agrees with him.

Obama did not only slay John McCain in November, he validated the left’s frustrations over George W. Bush. He may even be on his way to undoing Reagan.

And for that, liberals will give Obama an extremely long leash.

Marc Sandalow is the former Washington bureau chief for the San Francisco Chronicle. He teaches politics and journalism at the University of California’s Washington Center.