Barely a day goes by where we don’t see a new poll trumpeting Donald Trump’s double-digit lead nationally among Republican voters.

Not all Donald Trump supporters are equal, however: Voter data released by Resonate reveals that Trump’s appeal lies largely with historically unengaged and uninformed voters. The resulting “influence gap” between Trump’s core supporters and those of his rivals could undercut for his staying power. To win the GOP nomination, Trump will need to figure out a way to expand his appeal beyond his core supporters and win the support of influential voters and activists.

“Voter engagement” is a continuum which starts with issue awareness and voter turnout (“Issue Voters”), ramps up through “Informed Voters” who follow one or more issues closely, “Invested Voters” who donate to campaigns, and finally “Influential Voters” who share their thoughts and volunteer on behalf of campaigns. It’s about quantity and quality of support – with more engaged voters attracting the support of their peers. When compared to all Republican primary voters, here’s where Trump supporters fall in the “political engagement” spectrum in a poll we conducted earlier this summer.

Trump supporters lag behind Republican primary voters in general in high-engagement voter categories. Trump also lags significantly in penetration of issue-driven voters. Conversely, he enjoys a significant concentration of support among unengaged voters. One might assume that these unengaged voters are attracted to Trump’s brash style and talent for creating sound bites. But will these voters become sufficiently engaged to carry him to the GOP nomination?

Overall, Trump supporters are less engaged than the average likely primary voter, with a significant drop-off in one key area: They’re less informed on the issues. They’re less likely than GOP primary voters to vote for a candidate based on the issues and they’re less likely to follow a particular issue.

Therein lies the potential roadblock for Trump’s continued success: his supporters appear less influential and have been less involved than those of his rivals and less engaged on the issues. These low levels of engagement are especially problematic in states that caucus, like Iowa and Nevada.

Caucus members are inherently invested in the political process and more informed on the candidates and issues. As a result, they’re extremely influential with friends and family, and are trusted among their peers. In other words, their voting patterns tend to have a domino effect on the general electorate. The more influential and engaged a candidate’s supporters, the more likely their support will impact other primary voters and the more likely they will be reliable volunteers and donors.

Trump’s problem, however, is deeper than just the votes. It’s about what leads up to the primary election itself – those volunteers who are willing to give a piece of themselves and the donors that write the checks. Trump is a well-funded candidate, and isn’t as reliant on donations as some of his adversaries will be throughout the primaries. However, donations are good for more than just funding advertising. People who donate to a campaign feel invested in their candidate. It’s more than just the dollars – it’s about being part of a larger movement they want to see succeed.

Big ad spends do not replace the legwork of field staff and volunteers at every precinct. We might therefore expect Trump to under-perform his poll numbers, relative to candidates with more-engaged supporters and volunteers who are invested (literally) in their candidacy. Those voters are predisposed to get out, spread the word and show up at the polls. President Barack Obama’s victory, for example, was as much a result of the campaign’s ground game and fundraising tactics as it was a result of its revolutionary use of data.

To translate his core support into success at the polls, therefore, Trump must expand his appeal beyond his base and build support among more influential and engaged voters. He also needs to give his existing supporters a reason to get involved in ways they never have before. Trump will continue to make headlines, but whether those headlines translate into voter engagement remains to be seen.

This column, written by Michael Horn at Resonate, originally appeared in U.S. News & World Report