Vice President Kamala Harris talks about climate change at Georgia Tech on Wednesday, Feb. 8, in Atlanta. AP Photo/John Bazemore

President Joe Biden is still old. That observation might not seem quite so relevant after Biden delivered a spirited State of the Union address Tuesday night that accomplished all the White House could reasonably have hoped for. Biden, 80, rattled off meaningful achievements, slathered on some bipartisanship with a salute to GOP Senate leader Mitch McConnell and praise for former President George W. Bush and then baited Republican House members into behaving like Republican House members, a performance that inevitably makes Biden and his party look like the only game in town for serious people of any age.

Biden was quick on his feet, exploiting his political foes in real time. His performance will deflate questions about his age for months. Maybe weeks. Or, as the existence of this column suggests, perhaps for a few minutes. The respite will necessarily be short. Because unlike most of the preoccupations of MAGA land, Biden’s age is a legitimate concern. He has had a tremendously successful half term and his White House has performed well. But he’s old and getting older; that makes supporters nervous and opponents ambitious.

Biden can’t do much about time past or future. But if he is going to run for reelection — and there is no reason to believe he won’t — he should do what he can to minimize the unease that eight decades of living induces in the electorate. The best thing he can do is have a vice president who is perceived as ready and able.

He doesn’t yet have that.

Here are some words from the first paragraphs of a Feb. 6 story in the New York Times about Vice President Kamala Harris: “Struggling.” “Frustrated.” “Trap.” Then comes “struggled” again. The Times story was the latest entry in the “Harris Can’t Cut It” genre, a growing body of reportage about her shortcomings on the national stage. A particularly brutal paragraph encapsulates the theme:

But the painful reality for Ms. Harris is that in private conversations over the last few months, dozens of Democrats in the White House, on Capitol Hill and around the nation — including some who helped put her on the party’s 2020 ticket — said she had not risen to the challenge of proving herself as a future leader of the party, much less the country. Even some Democrats whom her own advisers referred reporters to for supportive quotes confided privately that they had lost hope in her.

Harris’s bad press isn’t a result of attacks from opponents. It’s a result of a lack of confidence among allies. That’s partly Harris’s fault. The vice presidency may be a rotten job, but history — including Biden’s ascension to the presidency — proves it isn’t always a no-win job. Every vice president has to identify a downhill trajectory, commandeer gravity and make a political vehicle out of an engine-less soap box derby car.

One person who can make that task easier is the president of the United States. Harris’s main job until now has been sticking around Washington to cast tiebreaking votes in the Senate. It’s as mundane as it is essential — the sort of mechanical job that the president could highlight or ignore. Biden has mostly ignored it.

Making Harris the administration’s point person on the southern border is an even more thankless task. The border will be under stress — and continue to deliver talking points to demagogues — as long as millions of people view it as a final destination in their flight from misery. You cannot “fix” that problem without a comprehensive solution that only Congress can supply. (Even Congress will need coordinated assistance from other nations.) Neither Congress nor the nations producing desperate migrants are poised to ease the stress anytime soon. So the perception of a festering problem will remain.

Harris, 58, isn’t untalented. She rose through the ranks of the Democratic Party of California, hardly a political backwater. She won big statewide races for attorney general and U.S. Senate. In the Senate, she ably grilled former Attorney General William Barr among other slippery witnesses. Her 2020 presidential campaign didn’t catch on. That doesn’t mean she’s out of the running: None of Biden’s presidential campaigns took flight until the one that finally did.

It’s Biden’s job to bolster Harris, elevate her and convince first Democrats, then the wider electorate, that his vice president is prepared for the top job in the event the actuarial tables scramble the political scene. Biden selected Harris in the first place because he needed the qualities that she brought to the ticket.

He still does.

Francis Wilkinson is a Bloomberg Opinion columnist covering U.S. politics and policy. Previously, he was an editor for the Week, a writer for Rolling Stone, a communications consultant and a political media strategist.