When U.N. Ambassador Nikki Haley shocked the political world by abruptly announcing her resignation just weeks ahead of the midterm elections, speculation immediately spread that she planned to run against President Trump in 2020. But she isn't going to run against Trump in 2020 — instead, the move sets her up nicely to run against Vice President Mike Pence in 2024.

Nothing about Haley's move is consistent with what you'd expect if she decided to challenge a sitting president, even if we dismiss her assurances that she would not run in 2020 and would campaign for Trump instead.

[READ: Nikki Haley's letter of resignation]

Were a high-ranking official going to resign to challenge a sitting president, one would expect that person to do so dramatically, in opposition to something the president did — with an op-ed, public statement, and media blitz effectively launching the campaign.

In this case, Haley announced her plans alongside Trump, and both of them were all smiles as she said she would stay on toward the end of the year. She also praised the Trump presidency for helping to restore U.S. standing in the world by following through on his words on trade, the use of chemical weapons in Syria, demanding more contributions from other NATO nations, moving the U.S. Embassy in Israel to Jerusalem, and so on. "The U.S. is strong again," she said. This is not exactly a rallying cry for changing course.

Furthermore, challenging Trump would make no sense. Trump's approval rating among Republicans is at 87 percent — and whatever vestiges there were of the "Never Trump" movement have likely left the party by now. If Trump draws a challenger, it will be either somebody young and obscure, or an older politician with no future career ambitions — in other words, somebody with nothing to lose.

Haley, a savvy 46-year-old politician with a bright future, who has been careful not to burn her bridges either with Trump's supporters or his skeptics within the party, isn't going to blow up all her careful work in a hopeless bid just to make a handful of columnists happy. She's playing the long game.

She accomplished all that she needed to by being U.N. Ambassador. First, she gained foreign policy credentials, which is usually the biggest obstacle that governors face when running for president. Second, she mended fences with the dominant Trump wing of the party, after having been harshly critical during 2016. Back then, she endorsed Sen. Marco Rubio, R-Fla., and even needled Trump while delivering the GOP response to President Barack Obama's final State of the Union speech. Putting in another two years at the U.N. wasn't going to gain her anything else, and it carries potential risks — not knowing, for instance, what Robert Mueller may turn up or how any impeachment fight would go if Democrats go that route should they take over the House.

Now, she can remain in the public spotlight as much or as little as she wants, probably write a book, go on TV regularly, and be cheered in front of conservative crowds. And where she will be untainted by whatever happens within the administration beyond this point.

Haley can carefully see how the Trump phenomenon ages, and position herself however she needs to once he exits the scene. As she gears up for 2024, if Trump's brand has become more toxic, she can distance herself from his administration — saying first and foremost she was serving the nation as ambassador before the world. But if her association with Trump is a boost, she can play up the fact that she loyally served him.

Pence, on the other hand, has placed his bet entirely with Trump, for better or for worse. He has the claim of working more closely with Trump than anybody else. If that's what the 2024 Republican electorate is craving, then it will give him an advantage. However, if by that time Republicans want somebody with more distance who isn't necessarily seen as being anti-Trump (such as Sen. Ben Sasse), then it would give an edge to Haley.

Obviously, it's way too early to game out 2024 in much detail. What we can say is that Haley's move today does not make any sense if she's looking to challenge Trump in 2020, but it is consistent with what you'd expect from a young politician who is thinking beyond the next election.