President Obama this week called the war in Afghanistan one of "necessity," not choice. It is, he proclaimed, the "central front in the war on terrorism ... where the Taliban is gaining strength. ..." He solemnly concluded, "This is a war that we have to win."

All this is true. But keeping his promise to win the "good" war in Afghanistan won't be easy. The president will face many tests along the way. Starting now.

The first test is in responding to the outcome of Thursday's elections in Afghanistan. The Obama administration has not yet figured out how to integrate successfully its nation-building efforts at the central government level with the much harder work of dealing with local factions and tribes susceptible to Taliban intimidation.

If the elections simply ratify the status quo in Kabul, the disconnect between central and local governance will likely continue. Corruption is undermining the legitimacy of the Afghan government, and legitimacy is critical in building up a strong Afghan army -- as well as U.S. counterinsurgency efforts in the countryside. Until corruption is at least minimized, the war cannot be won.

The second test is whether Mr. Obama will back his new strategy in Afghanistan with the resources needed to make it work. The administrations policy, unveiled in March, puts a high priority on protecting Afghan civilians as part of a counterinsurgency strategy.

There is already pushback from some Democrats who insist the Afghan "quagmire" will cost too much and drain resources from domestic programs. Mr. Obama's habit of trying to have it both ways -- tacking back and forth between tough and soft statements and ultimately splitting the difference on policy -- may not convince these Democrats in the long run. Mr. Obama will probably end up trying to keep his liberal critics at bay by giving Gen. Stan McChrystal fewer troops than he needs.

That would produce an ever-worse dilemma down the road. Insufficient troops will minimize battlefield success, ultimately prolonging the war. The longer the war lasts, the more criticism Mr. Obama will face from his political base. Time is not on his side politically, and his antiwar position on Iraq actually puts him in a politically weaker position than former President George W. Bush was on war policies. Mr. Obama's base is not only more hostile to some of his policies, but far less patient should he make unpopular decisions.

That could lead to Mr. Obama's third big test - one that could actually be his undoing. Whether the president knows it or not, his biggest allies on Afghanistan are pro-national security conservatives. Yet he still gives defensive speeches, as he did this week before the Veterans of Foreign Wars, attacking Sen. John McCain of Arizona and other conservatives over the war in Iraq.

This makes no sense. If he is serious about winning in Afghanistan, he needs to stop this divisive rhetoric and realize that his Afghan policies face a potential challenge from the right flank as well.

So far, most conservatives are holding strong behind the war effort. But there already are rumblings among some conservatives that "Obama's war" may not be worth fighting. Far more threatening than traditional isolationist or libertarian antiwar arguments are so-called conservative realists who may conclude that only a minimalist effort is all that is possible - or worse, needed - in Afghanistan. Such people may come to think that the U.S. is caught in the "graveyard of empires," a place where the more we try to do, the worse the problem gets.

It's not that Mr. Obama will face a conservative revolt against the war in Afghanistan. But when he needs conservatives to face down the dovish left wing of his own party, he may not find them eager allies.

True, some Republicans such as Mr. McCain are strongly supportive and will likely remain so until the bitter end. But that is not true for all Republicans in Congress. Facing a president doing battle with them on domestic issues, some Republicans may not be all that interested in providing political cover for "Obama's war." This would be wrong-headed; yet it is a political reality and, frankly, a price the president can expect to pay given his fiercely partisan approach to the Iraq war, as well as domestic issues.

Mr. Obama can pass these tests only by devising a workable strategy on Afghanistan and sticking to it, much like Mr. Bush did on Iraq, for as long as necessary and no matter what the political fallout.

Does he have the skills - and most importantly - the character to do this? Given all the bodies cast under the presidential bus to date, there is little so far to suggest that he does. And that would be a shame.

What's at stake is not just whether history remembers Barack Obama as the president who lost Afghanistan. It's about national security and which side prevails in the conflict between freedom and international terrorists.

Kim Holmes is vice president of foreign- and defense-policy studies at the Heritage Foundation.