Critical blasts erupted from the Democratic Party's left wing when the White House indicated President Barack Obama could include Social Security and Medicare cuts in a bipartisan multitrillion-dollar deficit reduction package.
MoveOn.org used adjectives like "stunning" and "sickening."
Economist-columnist Paul Krugman accused Obama of sharing the GOP's right-wing economic views. Firedoglake.com's Jane Hamsher said it meant "the death of the Democratic Party."
Though Republican critics regularly accuse Obama of liberal, even socialistic policies, many liberal Democratic groups argue that he has been too timid, even conservative, on issues from gay rights to the environment.
So far, there is no sign he faces a liberal challenge as the late Sen. Edward Kennedy mounted in 1980 against Jimmy Carter. But steady criticism has raised questions about whether lack of liberal enthusiasm could damage Obama's re-election bid.
Statistical evidence doesn't support that concern, at least not yet.
The Gallup Poll shows Obama's early July support among liberal Democrats at 86 percent, virtually the same as the month before, although he suffered modest declines among moderate and conservative Democrats.
And while his job approval has dropped 20 points from post-inaugural highs, that mostly occurred among Republicans and independents who didn't vote for him.
Still, friendly fire attacks persist, even though Obama is presiding over the most liberal administration since Lyndon Johnson's Great Society in the 1960s.
Supporters say he has gone as far as politically feasible, given the primacy of economic issues and virtually solid Republican resistance.
Still, it's hardly new for liberal Democrats to complain their candidate or president is insufficiently liberal and jeopardize his election, even if that helps a conservative Republican rival. (Similarly, some on the right thought Ronald Reagan's presidency insufficiently conservative.)
Liberal Vietnam War opponents abandoned Democratic nominee Hubert Humphrey in the 1968 election that Republican Richard Nixon won narrowly. Kennedy's 1980 primary challenge contributed to Carter's defeat by Reagan.
And in 2000, some outspoken liberals supported maverick consumer activist Ralph Nader over Vice President Al Gore, contributing to the Democrat's loss to George W. Bush.
Besides government entitlements like Social Security and Medicare, current liberal disquiet about Obama includes these areas:
Environment. Two prominent Democrats, Gore and former Interior Secretary Bruce Babbitt, sharply criticized Obama recently for failing to do more to preserve the environment. Gore, in a lengthy Rolling Stone essay, said Obama failed to take "bold action" on global warming, though he has tightened anti-pollution fuel economy standards for cars and spent heavily on alternative energy projects. Babbitt calls Obama "timid" in defending the environment.
Equal rights. Though Obama sought and won repeal of the military's "don't ask, don't tell" policy for gays and lesbians and withdrew government support from the law barring same-sex marriages, rights groups fault him for failing to endorse the legalization of such marriages.
Hispanics. Advocacy groups criticize Obama for increasing enforcement of laws requiring deportation of illegal immigrants and failing to do more to pass a comprehensive immigration bill providing a path to legal status. However, Obama sought, and Congress rejected, the DREAM Act, which would give legal status to illegal alien students after a specified amount of higher education or military service.
Foreign policy. Liberals who backed Obama in 2008 because of his early opposition to the Iraq war now want a faster withdrawal and oppose his increase of troops in Afghanistan and intervention in Libya.
Top White House strategist David Plouffe said last week Obama can count on continued strong support from younger voters and minorities, whose share of the electorate may grow from 2008.
Democrats also expect to benefit from conservative GOP policies and candidates among liberals, as well as organized labor, young voters and Hispanics -- who have been the target of Republican-sponsored measures in many states.
Carl P. Leubsdorf is the former Washington bureau chief of the Dallas Morning News. Readers may write to him via e-mail at: firstname.lastname@example.org.