In public and in private, Elon Musk is increasingly treating the prospect of President Biden's re-election as an urgent — even existential — threat to America.

Why it matters: Musk hasn't endorsed former President Trump. But the billionaire X owner has made no secret of his disdain for Biden's policies, leveraging his massive online platform to denigrate Democrats and promote Trump's messaging on the 2024 election's top issues.

• Chief among them is immigration. Musk has shared the conspiracy theory that Biden is intentionally "importing" millions of undocumented immigrants to boost Democrats' political power, as well as numerous posts portraying immigrants as security threats.
• "There is either a red wave this November or America is doomed," Musk posted this weekend, responding to a video about New York City's migrant crisis. "Imagine four more years of this getting worse."

The big picture: Musk's remarkable political evolution had begun at least by 2022, when the Tesla CEO revealed he had voted Republican for the first time.

• Musk, who said he would support Florida Gov. Ron DeSantis for president, called Democrats "the party of division & hate" and cast the debate over "woke" culture as a "battle for the future of civilization."
• Musk said he'd voted for Barack Obama, Hillary Clinton and Biden in the past, but called on "independent-minded voters" to back Republicans in the midterms.
• At that time, Musk's political messaging often focused on things like taxes and COVID policies — the issues he said motivated him to relocate Tesla from California to Texas. He also began to engage with right-wing commentators in opposing "woke-ism."

Today, a review of Musk's X feed suggests illegal immigration has become an object of near-singular obsession.

• "If Dems win President, House & Senate (with enough seats to overcome filibuster), they'll grant citizenship to all illegals & America will become a permanent one-party deep socialist state," Musk posted last week.
• Earlier this month, Musk accused Biden of "treason" and warned the administration was "creating a national security threat from unvetted illegal immigrants."
• "It is highly probable that the groundwork is being laid for something far worse than 9/11. Just a matter of time," he predicted.

Zoom in: Musk, who privately met with Trump in Florida earlier this month, was pressed on his views of the former president and the racist "great replacement theory" in an interview with Don Lemon released Monday.

• Musk said he may endorse a candidate "in the final stretch" of the campaign, and defended the immigrant conspiracy theory as "a simple incentive to increase Democrat voters."
• After the interview was taped last week, Musk abruptly canceled Lemon's partnership with X.

Between the lines: SpaceX's role as a major government contractor has historically made Musk reluctant to embrace traditional partisanship, according to the New York Times.

• Trump's skepticism on climate change has also been a source of past friction with Musk — one that could drive him into the arms of a third-party candidate like Robert F. Kennedy Jr.
• But one thing is certain: Through his anti-Biden crusade — and his shaping of X as a public square for the right — Musk's political influence will be put to the test in 2024.