Trump is weaker among independents than Republicans in primary polls

Former President Donald Trump holds a commanding lead in the Republican presidential primary, and is the clear favorite to win his party’s nomination. He’s polling in the mid-50s in 538’s national polling average, and holds substantial leads in most polls of early voting states.

That doesn’t mean, however, that Trump doesn’t have potential vulnerabilities. Primary polling suggests that Trump is not performing as well among Republican-leaning independents and unaffiliated voters who plan to vote in the GOP nomination race as he is among self-identified Republicans. And past Republican presidential primaries have demonstrated that independent voters can make up a significant chunk of the electorate in early voting states and, if their preferences differ markedly from Republicans, can influence outcomes.

To be clear, Trump usually leads among independent voters in primary polls — just by smaller margins than he does among self-identified Republicans. In what may be an obvious point, his large advantage among Republicans matters a great deal considering far more Republicans will vote in the GOP contest than independents (or Democrats, for that matter). During the competitive periods of the 2008, 2012 and 2016 Republican presidential primaries, around 70 to 75 percent of primary and caucus voters identified as Republican, according to ABC News’s aggregate exit poll data, while about 20 to 25 percent identified as independent or something else (5 percent or fewer identified as Democrats). But if the Republican race does tighten in the next few months, the preferences of independent voters could matter, particularly in New Hampshire, which has one of the largest blocs of unaffiliated voters of any state in the country.

Throughout the campaign, we’ve seen Trump perform better among Republicans than among GOP-leaning independents in primary polls. For instance, a May 2023 Quinnipiac University poll found Trump attracting 60 percent among Republicans, but just 46 percent among Republican-leaning independents. Earlier this month, Quinnipiac found Trump pulling in 67 percent of Republicans, compared with 47 percent of GOP leaners. And across national surveys conducted since Aug. 1 with available crosstab data, we usually saw a meaningful gap in support for Trump between Republicans and independents.

Now, different pollsters used different approaches to measuring public opinion, and some asked their questions to Republican and Republican-leaning registered voters (e.g., Quinnipiac), while others asked likely primary voters (e.g., Echelon Insights). These sampling differences could affect the results because a likely voter is, well, more likely to actually vote than the average registered voter who is a GOP-leaning independent. And while there’s general overlap between the party a voter is registered with and the party that voter identifies with — at least in the states with party enrollment — that’s not always the case, and some pollsters based their party affiliation data on reported registration while others asked for party identification. Additionally, it’s important to note that the sample sizes for independents in primary polling tend to be much smaller than for partisans, so in some cases the differences in Republican and independent attitudes aren’t outside the margin of error, which is always larger among subgroups within a poll. Yet the preponderance of evidence suggests that Trump does indeed perform worse among those who don’t outright identify as Republican.

We’re also seeing the split between Republicans and independents in state-level polling, too, which is important because parties don’t use a national primary to determine their nominees. Instead, they employ a sequential, state-by-state process in which the places that vote first influence — sometimes more, sometimes less — the elections that follow. So if the race becomes more competitive than it is right now, independents who cast a ballot in the GOP primary could influence the outcome, especially in independent-rich New Hampshire.

Critically, New Hampshire has both a large number of independents and allows them to participate in party primaries. As of Aug. 1, 38 percent of New Hampshire voters were registered as “undeclared” — that is, independent — while the other 62 percent were almost evenly split between the two major parties. This gives New Hampshire one of the largest blocs of registered independents among the 31 states that have party enrollment. New Hampshire also permits independents to cast ballots in the party primary of their choosing, whereas many states have closed primaries or caucuses that only permit party registrants to participate. As a result, exit polls have routinely found that self-identified independent voters make up a larger share of the Republican primary electorate in New Hampshire than in the other three early voting states of Iowa, Nevada and South Carolina.

New Hampshire’s 2024 GOP primary could have an especially high rate of participation among independents, too, because it will be the only seriously contested primary on the state’s ballot. President Biden faces no serious opposition, so more independents — even some who lean Democratic — might see the Republican primary as the only race worth voting in. We’ve seen this happen before: In 2012, when Democratic President Barack Obama was seeking reelection, the New Hampshire GOP primary electorate split almost 50-50 between Republicans and independents, according to the exit polls. By contrast, when Democrats also had competitive contests in 2008 and 2016, clear majorities of Republican primary voters in New Hampshire identified as Republicans. In line with this, the exit polls also found the share of voters who were registered as independents before voting in the Republican primary was higher in 2012 (45 percent) than in 2008 or 2016 (34 percent and 36 percent, respectively).

Now, Trump holds a sizable edge in New Hampshire, but surveys have also found Trump performing much better among Republican voters than among independents. And if Trump’s advantage in the race were to narrow, history suggests his relative softness among independents could conceivably boost his opposition. For instance, John McCain and Mitt Romney ran about even among self-identified Republicans in the 2008 New Hampshire primary, but McCain edged Romney among independents and won the state (and, eventually, the GOP nomination).

While independents are less likely to play a major role in other early states, surveys from Iowa and South Carolina (we have no recent Nevada polls) suggest Trump also has less support among them. However, Iowa and Nevada Republicans both utilize closed caucus systems where participants must be registered as Republicans to participate, which will likely benefit Trump. South Carolina, on the other hand, uses an open primary system because the state has no party registration, so that makes it easier for independents to participate. Still, past exit polls suggest we shouldn’t expect much more than 30 percent of GOP primary voters there to identify as independent. Trump has mostly polled in the mid-to-high 40s in South Carolina, but independent voters could matter in a close race: Similar to New Hampshire, McCain won South Carolina in 2008 partly thanks to outsized support from independents while he and former Arkansas Gov. Mike Huckabee ran about even among Republicans.

If Trump’s relative weakness among independents holds up once voting begins next year, it will represent a notable shift in his base of support compared to his first run in 2016. Back then, Trump performed similarly well among Republicans and independents, attracting 42 percent support among Republicans and 38 percent among independents during the competitive part of the primary (until early May 2016). Yet this time around, he may have more overwhelming backing from Republicans than independents, in part because, in a reversal from 2016, he’s getting somewhat more support from very conservative voters, who are more likely to identify as Republican, than from somewhat conservative or moderate voters. When it comes to winning the GOP nomination, though, that would almost certainly be a good trade-off for Trump.