Despite President Donald Trump urging South Carolina Republicans to turn out in Saturday’s open Democratic primary to vote for Sen. Bernie Sanders (I-VT), the Washington Post’s exit poll shows very few did.

Trump has openly encouraged Republicans in other states with open primaries — primaries in which state residents of any party affiliation can participate — to attempt to skew the vote in past 2020 primary contests. He did so again during a Friday rally in North Charleston, South Carolina, taking an informal audience poll on which Democratic candidate his South Carolina supporters felt would be easiest to defeat (Sanders “won” by drawing the loudest cheers from Trump’s audience).

“Are you ready? You ready?” Trump asked his South Carolina crowd. “Let’s do it together — I assume this is okay from a campaign finance standpoint, I assume. First we have to figure out who would be the weakest candidate against President Trump.”

Related Live results for the South Carolina Democratic primary

Sanders — a self-declared democratic socialist — was declared the easiest candidate to beat come November 2020, even though head-to-head matchup polls don’t necessarily bear that idea out.

Despite Trump’s urging, an exit poll from the Washington Post showed just 5 percent of registered Republicans actually voted in the primary, a number too small for pollsters to give details on which Democratic candidate received the most votes from that group. Registered Democrats made up 70 percent of everyone who voted in the primary, while independent voters accounted for 26 percent, according to that poll.

Both South Carolina Democrats and independents voted for former Vice President Joe Biden over Sanders; 54 percent of registered Democrats voted for Biden compared to 18 percent who voted for Sanders, and 35 percent of independents voted for Biden, compared to 23 percent who voted for Sanders.

South Carolina Republicans have already consolidated their support around Trump, and chose not to hold a Republican primary on Saturday. Trump has a 12 percentage point net approval rating in the state, and remains overwhelmingly popular among Republicans, with Morning Consult’s tracking poll showing 88 percent of GOP voters approve of him.

But that support apparently has limits. If Trump’s theory was that he could get his supporters to juice Sanders’s South Carolina numbers enough to change the outcome of the Democratic primary, he was wrong. Biden’s South Carolina victory was decisive, especially among black voters, who made up over half of the voters on Saturday. Overall, the former vice president received nearly 50 percent of the vote.

So while Trump remains an overwhelmingly popular and influential figure in South Carolina politics, the Democratic primary also served as a reminder that there are limits to what Trump can convince his Republican supporters to do.