President Barack Obama is an unremitting critic of George W. Bush, but in Afghanistan he’s walking in Bush’s shoes. How ironic. But also, how encouraging.

[IMGCAP(1)]Ironic, of course, because as a Senator, Obama was among the strongest critics of Bush’s 2007 troop “surge” in Iraq.

He predicted that additional troops would actually worsen the sectarian violence raging in that country — though by September 2008, he acknowledged that “the surge has been successful,” but “in ways that not even President Bush expected.”

Obama’s stance is encouraging because, like Bush in Iraq, he believes in the policies he’s pursuing in Afghanistan and is willing to buck opposition.

“We now have a strategy that can work. We’ve got one of our best generals today, [David] Petraeus, on the ground,” he told CBS on Monday.

“I’ve been very clear that we’re going to move forward on a process of training Afghans so that they can provide for their own security. Then, by the middle of next year, we’re going to start thinning out our troops and giving Afghans more responsibility.

“If I didn’t think that it was important for our national security to finish the job in Afghanistan, then I would pull out today, because I have to sign letters to … families who have lost loved ones.”

Opposition to Obama’s Afghan policy comes primarily from within the Democratic Party, of course, though there is also opposition from members of the U.S. foreign policy “establishment.”

So it was for Bush in Iraq. When the going got rough, prominent Democrats such as Senate Majority Leader Harry Reid (Nev.) declared the war “a lost cause” and a “quagmire,” and a majority of Congressional Democrats supported measures to curtail funding.

Congressional Democrats are turning against the Afghanistan War in increasing numbers, though opponents are still short of a majority.

Last week, 102 of the House’s 255 Democrats (plus 12 Republicans) voted against funding the wars in Iraq and Afghanistan.

Obama, who’s a nonstop critic of Republicans for opposing his domestic policies, owes GOP Members at least some thanks for supporting his Afghan policy.

But Democrats are not about to humiliate a president of their own party, and he is getting expressions of support from figures such as Senate Armed Services Chairman Carl Levin (Mich.) and Foreign Relations Chairman John Kerry (Mass.).

They would almost certainly be denouncing the Afghan war effort if Bush were pursuing it — as would Vice President Joseph Biden. The three not only opposed Bush 43 on Iraq but his father’s 1991 decision to go to war when Iraq invaded Kuwait.

In this case, Biden is forecasting that when Obama’s “thinning out” process commences next July, it probably will involve “as few as a couple thousand” soldiers. Biden, of course, argued against Obama’s “surge” when the policy was being formulated.

Obama also is sticking with his policy against mounting public dissatisfaction and expressions of doubt by “establishment” figures — most recently by Richard Haass, an official in both Bush administrations and now president of the Council on Foreign Relations.

Haass wrote in Newsweek last month that “It is time to scale down our ambitions there and both reduce and redirect what we do.” Haass does not favor a full-scale or sudden withdrawal, which “would almost certainly result in the collapse of the Karzai government and a Taliban takeover of much of the country.”

Rather, borrowing an idea from Robert Blackwill, a former U.S. ambassador to India, Haass favors “decentralization” — what amounts to partition — of Afghanistan, handing over Pashtun areas to the Taliban and equipping other ethnic groups to defend themselves.

This idea parallels ideas floated by foreign policy experts as alternatives to Bush’s Iraq surge— including a partition plan proposed by Leslie Gelb, Haass’ predecessor at CFR, and “redeployment” proposals by the Iraq Study Group.

The latest Gallup poll shows that — no doubt because of mounting U.S. casualty levels — a growing number of Americans (43 percent) believe that the U.S. made a “mistake” sending troops to Afghanistan, even though the question stipulated this first happened in October 2001.

That, of course, was a month after al-Qaida, then based in Afghanistan, toppled the Twin Towers. The memory seems to be fading.

Since then, some 1,220 U.S. service personnel have lost their lives in Afghanistan. Last month, 66 died, the highest monthly toll in the war.

However, that’s far short of the 4,400 who have died in Iraq and the record month, with 131 deaths, in May 2007.

As U.S. commanders have explained, the rising death toll is the result of increased military action to defeat the enemy. By 2008, the monthly average in Iraq was down to 26 deaths as the surge succeeded.

Of course, Iraq and Afghanistan are different countries. Petraeus’ counter-insurgency strategy may not work as well in Afghanistan as it did in Iraq.

And yet, it has to be tried. The United States has abandoned Afghanistan and its nuclear-armed neighbor, Pakistan, again and again — too many times to maintain our credibility as a superpower, should we do it again.

Obama is not giving up, much as Bush didn’t. We can only hope that both are vindicated.