President Joe Biden is reportedly set to announce that U.S. troops will be out of Afghanistan by Sept. 11, breaking the agreement the Trump administration signed with the Taliban promising a complete withdrawal by May 1.

This might seem like a short-term extension that simply allows Biden to negotiate better terms that do more to stabilize the U.S.-allied Afghanistan government from the Taliban after an American exit. But staying beyond the May deadline risks escalation on the part of the Taliban that, in turn, could potentially draw the United States into more years of conflict. There is, therefore, no guarantee that the 20th anniversary of the attack on the twin towers will actually be the end of America’s longest war.

While people have debated what staying in Afghanistan would mean for the fate of that country and the U.S. military, it’s not too early to also consider what the political implications of the president’s decision might be — and why they, too, argue for keeping to the May timeline.

Biden has got to where he is by being a good politician. Throughout the presidential election and the first few months in office, he has succeeded by sticking close to the center and focusing on the economic issues on which Democrats have popular support. So, it’s surprising to see him extend the stay in Afghanistan when he has an ideal window for a departure.

Biden wants to keep U.S. forces in Afghanistan a little longer — but out of harm’s way — to head off the political headache that would come with a collapse of the Afghanistan government. That outcome is likely after a May 1 withdrawal because the departure of U.S. troops is all but certain to strengthen the Taliban.

Unfortunately for him, that doesn’t seem to be an option. The Taliban stopped attacking American forces under the terms of the Trump deal, resulting in more than a year without any U.S. deaths. But the insurgent group has signaled it will begin attacking coalition troops again if they stay past May 1. So the choice is likely between leaving Afghanistan peacefully next month or again putting American forces under fire — making a withdrawal much harder to accomplish.

And even if those U.S. troops fare OK, Biden will also be placing pressure on himself to deliver a better deal than the one for which he’s derided Trump. Concerns about the consequences of the Trump arrangement focus on the possibility of a fall of the Kabul government and a Taliban takeover that would be disastrous for women’s rights. But neither of these concerns are likely to be alleviated over the next four months. In that case, Biden might feel obliged to remain longer still in search of something he can point to as an improvement over Trump’s deal that justifies a pullout.

Also consider that in May, Biden would have the excuse of sticking to a prearranged withdrawal plan; the next deadline is one that he himself has set. That means he has less ability to blame anyone else if things go wrong even as he has less leverage over the enemy. If attempts at diplomacy come up empty, leaving on that note might be seen as an administration failure in the way that sticking to the Trump plan would not have been.

It’s true that over the decades, Afghanistan has stayed out of the headlines for long periods of time even with U.S. soldiers dying in that country. There are two reasons why this time would be different, though, both of which make it likely Biden’s political standing would suffer if he allowed the American role in the war to once again escalate.

First, the status quo bias is one of the most powerful forces in politics, if not human psychology. In Afghanistan, U.S. soldiers are no longer dying, and an expectation has been created that America will be leaving by May 1. Going back on the deal, as Biden seems ready to do, could seem more like him starting a new war than continuing an inherited conflict.

Second, withdrawal is clearly identified with Trump as his own personal accomplishment. While Republicans like Rep. Liz Cheney want to stay in Afghanistan and would applaud Biden for doing so, the man whose voice is the party’s loudest and most dominant is clearly identified with withdrawing.

In 2024, if the U.S. has gotten drawn back into the conflict because Biden kept troops in Afghanistan past the May 1 deadline and withdrawal kept getting more difficult, Trump will be able to credibly argue that he signed a deal to end the war that Biden decided to continue.

How does Middle America respond to Trump’s pitch, made while standing next to Gold Star families, that every single one of the soldiers who died after May 1 would be alive if Biden had simply stuck to his agreement?

Unquestionably, there are also risks to Biden in leaving Afghanistan. If the government collapses in the aftermath of the U.S. withdrawal, it would generate negative headlines and denunciations from more hawkish members of Congress. But within a few years, no one in the U.S. would be thinking about Afghanistan, no matter how bad the situation there was. How often do we talk about Libya, a country that has suffered a decade of intermittent civil war since the U.S. overthrew its government?

In contrast, staying in Afghanistan beyond May will make the conflict a festering wound. And unlike previous presidents, Biden won’t have the advantage of the other political party being ambivalent about or even supportive of the war.

With Trump leading both the polls and the betting markets for the 2024 Republican nomination, continuing the war in Afghanistan would be a gift to his future campaign. Biden would be wise to consider this as he decides which path to take. If the president feels that he must stay for now, he must ensure that the Sept. 11 withdrawal deadline is the final one.