There's a lot of talk this year about third party runs for the presidency. Will Trump run as a third party candidate if he doesn't get the nomination? Will Sanders? How about Bloomberg if Trump gets the nomination? (OK, not Bloomberg)
There's a lot of angst.
To dispel that angst, let's talk about what a "third party run" means. Technically America has a multi-party election, but realistically, universal ballot access is limited to the designated nominees of the Democratic and Republican Parties. The barriers against other parties, independent candidates, and write-in candidates are significant.
Let's look at those three options:
Parties other than the Republican and Democratic PartiesThere are minor parties in the US electoral system. The most significant are probably the Libertarian Party and the Green Party. Aside from Ross Perot's 1996 run at the head of his Reform Party, the only other minor party to field a presidential candidate since Strom Thurmond (States' Rights Democratic aka Dixiecrat) and Henry Wallace (Progressive) in 1948 has been the American Independent party. No minor party candidate since 1968 has won a single electoral vote (EV) and the best percentage a minor party has garnered since 1968 is Ross Perot at 8.6% in 1996.
This year, the Libertarian Party claims they will be on the ballot for 342 (about 63%) of EVs. Technically enough to win, but they would need to win just under 80% of the EVs they are on the ballot for.
The Green Party says they have ballot access in about 20 states totaling 304 (about 56%) of EVs, which means they would need to win just under 89% of those EVs to elect a president. They do say that about another 179 EVs are "potentially in play", which at this date I interpret as "we pray we might get on the ballot".
For those of you watching the far-right, the Constitution Party hasn't managed to get on the ballot in over 41 states and in 2012 was on the ballot in only 26. They have never won a single EV and their high-water mark in votes was less than two-tenths of one percent (about 183,000 votes in 1996).
Since 1900, the best a third party has done is Teddy Roosevelt's Progressive Party in 1912, which gathered over 27% of the popular vote nationwide and 88 (16.5% of the then 531) EVs for a second place finish ahead of the rump Republican incumbent William Howard Taft (8 EVs) and far behind Democratic Party nominee Woodrow Wilson (435 EVs and 42% of the popular vote). This was the last election in which a non-Republican Party, non-Democratic Party candidate came second in EVs or the popular vote. Wilson won 40 of 48 states, Roosevelt 6, and Taft 2 (VT and UT, if you're counting). The popular vote was much closer, with Wilson gathering about 6.3 million, Roosevelt about 4.1 million, and Taft about 3.5 million.
Write-in CandidatesTechnically, Write-in candidates have access to 43 states and 494 (just under 92%) EVs. Thirty-five of those states require some sort of paperwork.
However, I can find no evidence that a Write-in candidate has ever made a respectable showing in a national presidential election. There are some notable primary wins, especially Henry Cabot Lodge in 1964 who won Republican Party primaries in New Hampshire, New Jersey, and Massachusetts.
And then there's the success that fails: in 1968 incumbent Lyndon Johnson did not file for the New Hampshire Democratic Party primary, gaining 50% of votes cast as a Write-in. However, Eugene McCarthy was on the ballot and received 41% of the vote. Johnson withdrew from the 1968 election, leaving McCarthy to lose massively to Republican Party candidate Richard Nixon.
Independent CandidatesSince 1912 the most popular "third party" candidate has actually been independent, running outside of the party system. In 1992 independent candidate Ross Perot gathered 18.9% of the popular vote while winning 0 EVs. In 1980 independent candidate John Anderson got 6.6% of the popular vote while winning 0 EVs.
To get on the ballot for November as an Independent, you have to deliver signatures to every state (except for Louisiana and Colorado, where you can just pay them). A grand total of about 875,000 signatures in 48 states plus DC, with 49 different requirements and 25 different deadlines.
The Bottom Line: non-major Candidates are spoilersWhile minor party, write-in, and independent candidates have garnered significant popular vote numbers in the last century, none have been viable national candidates as measured by the only metric that matters: EVs. Even Teddy Roosevelt didn't come close, and he was closer to a true Republican Party candidate than a true minor party candidate.
Any "third party" candidacy must be seen nearly exclusively in the role of spoiler. Yes, this is a weird year, with Trumpers and Berners showing great enthusiasm among polities that mostly seem unwilling to vote. "Likely voter" models are out the window, or at least deeply in question. Something wild could happen. But the last 100+ years (only 25 or so presidential elections, really, so the sample size is small) says it won't. The most recent President of the US who wasn't either a Republican or a Democrat was ... Millard Filmore (1850-1853), our 13th President who was a Whig.
The Republican Party and Democratic Party have dominated four of the six "party systems" covering US presidential election history, starting in 1854. There is no particular reason to think this is going to change. The Republican Party is likely to have to re-invent itself, as both of the two major parties have done periodically since the 1850s, when the Republican Party was the northern anti-slavery big government party and the Democratic Party was the party of Redeemers and Copperheads as well as the lower economic class rural workers now seen as the voting backbone of the modern Republican Party.
Could someone run?It's quite clear that the idea of a third party run is in the air. But the mechanics of such a run (other than a futile Write-in campaign) are difficult, and probably out of reach at this point, especially for a pseudo-Republican Party candidate like Trump.
The best route would probably be taking over one of the existing minor parties, like the Libertarians or the Greens. The downside of that is that you are immediately giving up huge swaths of the country and would have to win 80+% of the EVs where you are on the ballot.
Failing that, or desiring access to all the EVs, an Independent run is the only option. And there's a giant steaming pile of Texas* in your way. If you want to be on the November ballot as a independent in Texas, you have to deliver nearly 80K valid signatures. According to Politico, all of those signatures must come from voters who did not vote in the March 1st primary (taking more than 4 million likely voters out of the signature pool). By the 9th of May (39 days). About 2K valid signatures per day.
According to BallotPedia, the average cost per required signature is just over $4, so that's about $320K just in Texas. An average of $3.5 million nationwide. Some campaigns cost three times that, or about $10 million nationwide.
* The last Democratic Party candidate to win Texas was Jimmy Carter in 1976. The last Republican Party candidate to win the Presidency while losing Texas was Richard Nixon in 1968. It's hard to see a Republican Party (or pseudo-Republican Party) candidate winning the Presidency without Texas.
So if there are not Trumpers out gathering signatures to put Trump on the ballot in Texas, Trump is not running as an Independent.
Oh, and there's one other problem. Texas is one of two states with "sore loser" laws that apply to presidential elections. No one who has run in a presidential primary in Texas may be on the ballot as an Independent.
There is possibly some wiggle room. A court challenge might defeat the May 9th deadline (every non-presidential candidate in Texas has until June) and 42 out of 45 states with sore loser laws have established precedents that they do not apply to presidential primaries, so Texas may just be next on that list (the other state, BTW, is South Dakota, whose 3 EVs may or may not be worth the trouble). John Anderson ran as an Independent in 1980 despite participating in seven early caucuses and primaries, but had withdrawn well before the Texas primary.
Will someone run?Here's how you know whether it's going to happen.
At least not unless there is some very interesting activity going on at a relatively frantic pace. Now, or if not now, soon.
Look for news reports of signature gathering in Texas (deadline 5/9), North Carolina (deadline 6/9), and Illinois (deadline 6/27). If you don't see it, court challenges or taking over a third party are the only options, and I don't believe that taking over a third party is anything but a spoiler move.
Berners and Trumpers may stay home, or not. Clintonistas and Cruzers may hold their noses, or not. But the odds of a successful third party or independent run are tiny and the barriers are huge.
I think it comes down to one question:
If he doesn't get the nomination, is Trump crazy enough to spend millions just to defeat Ted Cruz?
Anybody who waits until after the conventions is giving up any chance to get access to more EVs than the Libertarian and Green Parties are already signed up for, so the secondary question is:
If he doesn't get the nomination, could Trump subvert either the Libertarian or Green Party and become their nominee?
I have no idea.
(updated: spelling corrections)