> Not recently for President,

Not ever. The Federalists collapsed before we got a Whig, and the Whigs before we got a Republican, and those and the Democratic (ex-Democratic-Republican) parties are the only four that have won the Presidency.

> but third parties have won at every other level of government including Governors, Representatives, and Senators.

Sure, but its easy to overcount them; state two-party systems (where they haven't been effectively one-party systems) haven't historically always aligned with the national two-party system (e.g., Missouri’s [ed: or, in the real world, Minnesota’s] Farmer-Labor Party was the second (and later first) party in the state for years, alongside the Republicans, before it merged with a local third party—and thereby joined the national Democrats—as the Democratic-Farmer-Labor Party.

I would consider Sanders to be a pretty legitimate third party candidate - VT democrats have coalesced around him recently but his initial bid for Senate was pretty spectacular. He managed to ride an extremely popular mayoral career into a state that is extremely dominated by Burlington population-wise. Burlington metro is roughly as large a proportion of the VT voting block as NYC metro is for NY.

> I would consider Sanders to be a pretty legitimate third party candidate -

While he identifies as a socialist by ideology and has some association with the Vermont Progressive Party, AFAIK he has always run for federal legislative office as an independent, not third-party, candidate.

> VT democrats have coalesced around him recently but his initial bid for Senate was pretty spectacular.

IIRC, his original House campaign was spectacular, but Democrats in VT coalesced around him in his 8 terms in VT’s sole House seat.

Oh excuse me yes - I'd forgotten he initially stepped into congress as a house rep.

It was MN not MO:

https://en.wikipedia.org/wiki/Minnesota_Farmer%E2%80%93Labor...

> It was MN not MO:

It was, and I am embarrassed that i managed to do that.

I would mention that everyone's favorite example in this category (Bernie Sanders) does secure the democratic primary nomination for senate each election - he just refuses to leverage it in the general election. But failing to do that would lead to a much harder general election since the Dems would likely put up a competing candidate and split the vote three ways.