Why Biden should run. And why he shouldn't.

President Joe Biden has been in an upbeat mood since the Democrats' best first-term midterm showing in 60 years — and no wonder. For a second straight election, he achieved his presidency's overriding goal of protecting the nation's democratic institutions from the Trumpian threat. And the results relieved any immediate party pressure for him to forgo a 2024 re-election bid.

In fact, last weekend's USA TODAY/Ipsos poll showed the percentage of Democrats wanting Biden to run and believing he would win up about 10% since August, though half still opposed his re-election candidacy.

Still, as Biden quietly marked his 80th birthday last Sunday, the basic Democratic dilemma remained: Will it be best for the party — and the country — to renominate the nation's oldest president, even if the alternative is chaos?

Biden's best argument for running again is that, as in 2020, he feels able to do the job and may be the only Democrat who can beat Donald Trump. But though Trump still dominates the GOP, its unexpectedly poor 2022 showing has more Republicans saying openly that it is time to move on.

Midterm election exit polls showed a higher percentage of voters opposed another race by Trump than opposed a second term bid by Biden.

The prospect of a 2020 rerun against Trump apparently animates the president's thinking. "Don't compare me to the almighty, compare me to the alternative," he likes to say. Of course, with a burgeoning GOP field, almost every alternative is younger and possibly more electable than Trump.

On the other hand, just as France's King Louis XV correctly predicted more than two centuries ago that his departure would prompt a "deluge," so too do the Democrats face the possibility that a post-Biden free-for-all could undercut their hopes of retaining the presidency.

But potential rivals need to consider that opposing the first Black, Asian American and female vice president would be tricky in the increasingly multiracial Democratic Party. Though Democrats have not yet set their primary calendar, a key early contest will almost certainly again be South Carolina, where the 2020 primary electorate was more than half Black.

And if Harris faces impediments, so do her potential rivals.

For Minnesota Sen. Amy Klobuchar and Commerce Secretary Gina Raimondo, it's the glass ceiling for women that contributed to Hillary Clinton's defeat.

For Transportation Secretary Pete Buttigieg, it's being an openly gay man with a husband.

For California Gov. Gavin Newsom, it's an image as a trendy California liberal.

Though Biden would be 86 by the end of a second term, he still seems inclined to seek re-election, as has every modern president. But the nation's oldest president has left the door ajar, if his health deteriorates or he and his family decide it's time to end his half-century political career.

"Our intention is to run again," Biden told his Nov. 9 post-election news conference. But he said it was "ultimately, a family decision" that would be made sometime early next year, though he added, "I think everybody wants me to run."

Not everybody outside the family circle. The Election Day exit polls showed a majority of independents and nearly half of all Democrats thought Biden should not run again.

But the pre-election expectation of post-election Democratic disarray focused on Biden's future didn't happen. Instead, Republicans are beset with internal strife after failing to meet their expectations of a "red wave" that would capture the House, the Senate and key governorships.

That disarray is providing the Democrats and Biden with a useful respite. If it persists, the House GOP focus on investigating instead of legislating may make him look good by contrast.

Meanwhile, continued good health may be the best way for Biden to allay concerns about his age, along with occasional videos showing him riding his bike. Though he skipped a dinner at the end of one long day, Biden last week completed an arduous, weeklong round-the-world trip to conferences in Egypt, Cambodia and Indonesia that showed him on top of the issues and very much in command.

Still, signs of his age show in his often awkward gait, verbal stumbles and sometimes less-than-forceful public speaking. A re-election campaign would be challenging both politically and physically.

In 2020, the COVID pandemic enabled Biden to avoid the usually hectic speaking schedule and campaign from his basement. That likely won't be possible in 2024.