Do you know who is polling third in the 2024 Republican race for president? That may feel like an odd question given that the two leading candidates, former President Donald Trump and Florida Gov. Ron DeSantis, are the only ones averaging over 5% nationally.

The answer, though, is former Vice President Mike Pence and former United Nations Ambassador Nikki Haley, both tied at just 4%.

More worrisome for Haley, who is taking part in a CNN town hall Sunday evening, and other candidates polling outside the top two is the seeming nationalization of the GOP primary process this year. We're seeing that reflected in state polling, including in the early voting and declared candidates' home states: All largely show a significant advantage for Trump.

Presidential primaries, unlike general elections, don't occur on the same day. They're sequential, with outsize importance given to the states that vote first. This is why you see Republican candidates flocking to Iowa (for its caucuses) and New Hampshire (for the first-in-the-nation primary).

In recent years, national polling leaders at this point in the primary season who would go on to lose their party nominations did so in part because they lost the Iowa caucuses. That happened to the two candidates with the largest national leads: Republican Rudy Giuliani and Democrat Hillary Clinton, each in 2008.

Both were clearly in trouble in Iowa at this point in the cycle. In fact, neither led their side's contests in Des Moines Register polling from May 2007.

2024 race goes national

This year, we're not seeing such a disconnect between national and early-state polling -- at least not yet. The top two candidates in Iowa and New Hampshire surveys released to the public have been Trump and DeSantis. A University of New Hampshire poll taken in mid-April, for example, had Trump at 42% and DeSantis at 22%. New Hampshire Gov. Chris Sununu, who is expected to announce his 2024 plans this week, was in third place at 12%.

Let's focus closer on that Sununu datapoint. A few years ago, I noted that one of the better ways to predict whether a candidate trailing in national and early-state polls could surprise people is by examining how they were doing in their home states.

At this point in the 2016 cycle, Sen. Bernie Sanders was already leading in the Vermont Democratic primary, despite Hillary Clinton's sizable national edge. On the other hand, former Maryland Gov. Martin O'Malley's lack of any polling strength in his home state made me dismiss him as a contender.

Home-state polling is a crucial early indicator of a candidate's strength. Voters there know these candidates best. If you can't break out where the voters already know you, how can you break out in states where voters are just getting to know you?

Sununu doesn't need to worry about name recognition in the Granite State. The same is true for Haley in South Carolina, where she used to be governor. South Carolina also happens to be the third state on the 2024 GOP nominating calendar, after Iowa and New Hampshire.

The most recent poll from South Carolina that meets CNN's standards for publication put Trump well out in front. The Winthrop University survey, completed in early April, had Trump at 41%, DeSantis at 20% and Haley at 18%. Her fellow South Carolinian, Sen. Tim Scott, came in at 7%. More recent data hints at Haley dropping a little and Scott climbing up in the weeks since, though Trump is still way ahead.

It's quite possible Trump keeps his lead and knocks Haley out of the race with a victory in the South Carolina primary. Remember, he did something similar in 2016, when he ended Sen. Marco Rubio's presidential bid by beating him in Florida.

Weaknesses in his armor?

Of course, you can spot where Trump is vulnerable, if you look hard enough.

For example, in Florida, DeSantis and Trump have been trading leads in polling this year.

And you can make the case that these early-state polls overall suggest that Trump is a bit weaker than the national numbers might indicate. On average, he's polling in the low-to-mid-40s in the early states versus in the mid-50s nationally. In other words, a majority of voters in the early states are going for someone other than Trump, which isn't true at the national level.

Can you imagine how devastating losing in New Hampshire or South Carolina -- or both -- would be for Trump? It would puncture a large hole in the idea that his nomination is inevitable.

For the moment, though, that scenario seems like a fantasy. Trump may be showing some weakness in the early-voting states but not close to the same degree as national front-runners who lost in years past.

Trump can be beat. It's just going to be really tough.