It wasn’t the few spectacular gaffes, like referring to Kamala Harris as "Vice President Trump." It was the groping for words, the meandering free associations, and the plain evasion of hard questions that failed to allay fears of fellow Democrats.

The performance, taken as a whole, simply reinforced the picture of Biden as a frail old man. He did himself no favors when he explained that he needed to pace himself better—can you imagine any other president saying that?—or told the whopper that his usual schedule is 7 a.m. to midnight.

Biden clumsily tried to deflect all the tough questions about his age and capacity to defeat Trump by changing the subject to his achievements. After lengthy digressions with dead ends, he seemed to get bored or confused by his own rambles, abruptly cutting himself off at several points.

In response to a question by NPR’s Asma Khalid about why he had changed his mind after describing himself in 2020 as wanting to be a transitional president to a new generation of Democrats, Biden replied that he realized, in office, that there is so much to do that he needed to finish the job. But that doesn’t mean he is capable of finishing the job, or of getting re-elected.

The press conference was barely over when Jim Himes (D-CT), the ranking Democrat on the House Intelligence Committee, called for Biden to stand down, followed by Scott Peters (D-CA) and Eric Sorensen (D-IL). Several others have broadly hinted that he should step aside, though not quite in so many words. These calls will only intensify when Biden sits for an interview with NBC’s Lester Holt on Monday, a one-on-one format that will make evasion more difficult and more painfully obvious.

Some say we are in the worst of both worlds: not quite bad enough to force Biden to step aside but sufficiently troubling that the drip will continue. But my own sense from talking with Democrats is that Biden’s performance was more than bad enough. For every Democratic member of the House and Senate who has publicly called for Biden to step aside, there are legions more giving the same message to the White House and the legislative leadership privately. Several more will soon go public. This can only end with Biden standing down.

Biden and his campaign advisers went all in on his stature as a foreign-policy president. The 75th anniversary NATO summit, with Biden as host, was ready-made as a backdrop.

But despite the boastful rhetoric, expansion of NATO, given Putin’s increasingly menacing threats, was not Biden’s personal achievement. The initiative to seek NATO membership came from the nations at risk. Biden does deserve credit for getting Turkey’s buy-in. The core foreign-policy challenge that prompted NATO expansion, an endless Russia-Ukraine war, is no closer to resolution.

Biden took a big gamble on the press conference. He is taking an even bigger gamble on a foreign-policy issue that Biden’s own future has crowded off the front pages: the possibility of a settlement between Israel and Hamas, which in turn could lead to a broader Mideast settlement or at least a de-escalation. That would be quite an achievement, for which Biden could fairly claim credit.

In the past two days, there have been detailed leaks to the effect that a deal is within reach. Biden, ever inclined to carrots rather than sticks with Netanyahu, even ended the pause in the shipment of 500-pound bombs to Israel, presumably for use in Gaza—a plain contradiction of the premise that Israel and Hamas are on the verge of a deal. But as explained in great detail by this piece in Haaretz, Netanyahu has systematically acted to sabotage the progress by moving the goalposts every time a deal with Hamas seemed close.

The tragedy of Biden’s situation is that his substantive discussion of complex foreign-policy issues was solid. He was able to go into knowledgeable detail on the Israel-Hamas negotiations, as well as respond well to questions on NATO’s demands of China. He’s well informed, but the infirmities of age are palpable.

The longer Biden stays in, the more questions of his fitness crowd out the issue that should be getting front-page attention every single day: Donald Trump’s grotesque unfitness to be president. In a one-hour press conference where Biden changed the subject more often than he did not, he seldom shifted the subject to Trump. That alone is disqualifying.