I don’t think the US would elect from a third party, for President.

Ross Perot won 19M votes - a full 19% of the total cast - in 1992. And that was after dropping out suddenly, then needing to reboot his campaign following a popular high watermark in June. At that point, Perot led the national public opinion polls with support from 39% of the voters (versus 31% for Bush and 25% for Clinton).

I think you're underselling how influential an outsider could be if both parties ran really disappointing candidates. It should be noted that Republican polling was in the garbage by the end of Bush 41's term, while Democrats suffered enormous structural headwinds (virtually every big state had a Republican lean in 1992).

It isn't that hard to imagine a 2028 campaign in which a turd like JD Vance runs against a Mondale-esque Democrat and the popular voting majority is woed by a Platner-style independent. Or a third-party George Wallace / Huey Long candidate tries to do National Socialism outside the two party system, with the backing of Silicon Valley tech trillionaires and media magnets.

Hell, we almost saw something similiar with the RFK Jr campaign (before he was bought off and brought in by Trump) in 2024. And Trump himself, after he threatened to run indie during the 2016 GOP Primaries. We actually saw something like this play out in 1912, when Theodore Roosevelt ran an independent campaign against his own former VP, Howard Taft, and consigned the GOP to a third place finish (while handing Woodrow Wilson a landslide win).