Washington DC - President Joe Biden belatedly joined TikTok on Sunday, marking his debut on the social media platform with a 26-second video.

The move comes after fierce US government criticism of the video-sharing platform in recent years, most notably from Republicans but also from the Biden administration.

TikTok is owned by Chinese firm ByteDance and has been accused by a wide swath of US politicians of being a propaganda tool used by Beijing, something the company furiously denies.

In Sunday's video posted on the @bidenhq campaign account, the 81-year-old Democratic president touches light-heartedly on topics ranging from politics to the NFL championship game.

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Asked his preference between the Super Bowl or its famed half-time show, this year headlined by singer Usher, he picks watching the actual game itself.

Queried if there's a secret plot to rig the game so that pop star Taylor Swift – who is dating Kansas City Chiefs star Travis Kelce – could use her fame to endorse Biden, the president jokingly leans into the unfounded right-wing conspiracy theory.

"I'd get in trouble if I told you," he says.

Citing security concerns, a slew of individual states and the federal government have banned the app on official government devices.

In Montana, a state government move to completely ban the app was recently blocked by a judge.

While the platform remains scrutinized by Washington, further federal action to ban or curtail use of the app appears to no longer be in motion.

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"It seems now like the idea of a ban was being pushed more so to make political points and less as a serious effort to legislate," David Greene, a civil liberties attorney, recently told The Guardian.

As the election approaches, the platform provides a conduit to young voters.

Sunday's video ends with the president being asked whom he prefers: himself or Republican frontrunner Donald Trump.

"Are you kidding?" he laughs. "Biden."