We can all agree that the recent Fourth of July holiday was not particularly festive, given the grim tidings on all fronts. But perhaps the unhappiest Americans these days are the antiwar liberal Democrats who voted with enthusiasm for Barack Obama, only to find him tethered to a protracted war in a remote region that for two millennia has foiled virtually every foreign invader. Even Alexander the Great had to flee with an arrow in his leg.

If George W. Bush were still in office and presiding over the same circumstances in Afghanistan, you can bet that liberals would be vocally apoplectic.

But with Obama on the hot seat, they're stuck. Even though Obama is basically trapped in this unwinnable war, even though he's using Bushspeak to talk about all the "progress" we've supposedly made in Afghanistan, liberals don't want to make his political life more miserable than it already is. So mostly they fume about their powerlessness.

Liberals have been relatively quiescent for a slew of reasons. For starters, they have the same war fatigue that afflicts most other Americans. Afghanistan (now officially the longest war in U.S. history) and Iraq are simply a drag to contemplate; it's easier to just tune them out.

They have been seething about Obama's flexible promise to begin troop withdrawals in July 2011 – but, truth be told, they haven't made a coherent case for a smart alternative policy. That's probably because there are so few alternatives. What happens if we leave Afghanistan on our timetable, and the terrorists now hunkered down in Pakistan take the opportunity to set up shop all over again?

The bottom line is that they're locked into this war, just like Obama. For most of the past decade, especially when Bush was fixated on Iraq, the liberal complaint was that America was rushing to avenge 9/11 by invading the wrong country. Liberals, eager to demonstrate that they, too, believed in the application of military force, saw Afghanistan as the right place for a just war – a chance not merely to defeat al-Qaeda on the battlefield, but to bring humanitarian aid to people who suffered at the hands of the Taliban.

Indeed, candidate Obama was quite clear about his plans for a wider war in Afghanistan. For instance, during a CBS interview in July 2008, he said: "I think one of the biggest mistakes we've made strategically after 9/11 was to fail to finish the job [in Afghanistan], focus our attention there. We got distracted by Iraq."

He said, with respect to Afghanistan: "For at least a year now, I have called for two additional brigades, perhaps three" – in other words, as many as 15,000 new soldiers. And that autumn, during his first debate with John McCain, he said: "We have seen Afghanistan worsen, deteriorate. We need more troops there. We need more resources there."

Did liberals not hear what he was saying? Maybe they figured he had to say those things about Afghanistan to ensure that he wasn't perceived as a Democratic softy; having invested in his campaign, liberals may have seen his stance as nothing more than shrewd politics. Mostly, I suspect that when he attacked the Iraq war and got hawkish about Afghanistan, what liberals actually heard in their heads was simply this: "I'm not a dummy like George W. Bush."

Nevertheless, a wider war in Afghanistan was a key feature of the "change" that liberals voted for, even if they chose not to see it at the time. The immediate political danger for Obama, however, is that the left's unhappy quietude might further depress Democratic turnout in the November midterm elections. With apologies to Alexander the Great, this dearth of enthusiasm could be the next arrow in the president's leg.

Philadelphia Inquirer columnist Dick Polman's e-mail address is dpolman@phillynews.com.