Finishing 2nd in New Hampshire has been mandatory to be president

Most polls point to Donald Trump winning the New Hampshire Republican primary on Tuesday. Right now he maintains a double-digit lead over any of his competitors.

The real question about New Hampshire's Republican primary is who will finish second — and third, and fourth. If history is any indication, these are actually very important outcomes.

In the past 60 years, no eventual nominee finished worse than second in New Hampshire. That means that, much like the Iowa caucuses, New Hampshire is more about who won't be president than who will.

New Hampshire has mattered historically. This year could be different.

The New Hampshire primary tends to be the place, historically, where two or so candidates rise to the top of the pile. Usually the second-place finisher takes at least a quarter of the vote — not enough to win, but still a healthy base.

The worst any eventual nominee performed was Barry Goldwater in 1964 with 22.3 percent of the vote, behind Henry Cabot Lodge at 35.5 percent.

After Goldwater, the worst New Hampshire performances among eventual primary winners were Bill Clinton in 1992 (24.8 percent), Bob Dole in 1996 (26.2 percent), and Walter Mondale in 1984 (27.9 percent).

But this year might be different: Most polls show Ted Cruz, Marco Rubio, John Kasich, and Jeb Bush all settling in between 9 and 16 percent. So unless there's an unexpected swing, the second-place finisher will probably not garner more than 20 percent of Republican primary-goers.

Eventual nominees from the past 60 years have never finished this poorly in New Hampshire.

A case for why New Hampshire matters less this year

The past two Republican election cycles had both a leading conservative candidate and a top moderate candidate. Iowa helped pencil in the line of where voters would split between the two, and New Hampshire helped ink that line in a more permanent way.

The two contests helped define which candidate got to claim each role.

For example, in 2012 Rick Santorum claimed the very conservative vote in Iowa, while Mitt Romney held the somewhat conservative and moderate vote. By New Hampshire, Romney had taken control of the election, although Santorum still had a large chunk of voters who were very conservative.

In 2008, Romney and John McCain shared the moderate vote in Iowa, while Mike Huckabee was the favorite among the very conservative and somewhat conservative crowd. By New Hampshire, Huckabee wasn't a factor, though he still drew very conservative voters; meanwhile, McCain had the moderate vote while Romney had the conservative one.

But this year, trying to articulate the line drawn in Iowa is much harder. The entrance polls for the Iowa caucuses show this fascinating split:

• Cruz was the favorite among "very conservative" voters, with decreasing support from more moderate voters.
• Rubio was the favorite among "somewhat conservative" voters, although he had a decent amount of support from moderates.
• Trump was the favorite among "moderate" voters, although he had respectable numbers among conservatives.

In addition, Kasich and Bush are polling at around 10 percent. So if anything, the only line that might be further defined is Trump voters.

What happened in the past when the party didn't like the people who finished in the top two?

It's only happened once since 1952, when the New Hampshire primary first became an influential election — and it happened that year.

Tennessee Sen. Estes Kefauver defeated President Harry Truman in New Hampshire, and Truman dropped out of the race. And he earned the most votes in primary elections. Here's a map to prove it:

Democratic 1952 primary by state by Vector map by Lokal_Profil and ThrawnRocks, used under the Attribution-ShareAlike 3.0 Unported license.

But party leaders didn't like Kefauver. His investigations into organized crime and corruption reflected poorly on Democratic governors and mayors. So even though he had won the majority of primaries, when the convention came around, the party rallied around Illinois Gov. Adlai Stevenson II. So since the New Hampshire primary started mattering, Stevenson is the first and only person not to place in the top two but still be the party's nominee.