To increase COVID-19 vaccine uptake in resistant populations, such as Republicans, focus groups suggest that it is best to de-politicize the issue by sharing five facts from a public health expert. Yet polls suggest that Trump voters trust former President Donald Trump for medical advice more than they trust experts. We conducted an online, randomized, national experiment among 387 non-vaccinated Trump voters, using two brief audiovisual artifacts from Spring 2021, either facts delivered by an expert versus political claims delivered by President Trump. Relative to the control group, Trump voters who viewed the video of Trump endorsing the vaccine were 85% more likely to answer "yes" as opposed to "no" in their intention to get fully vaccinated (RRR = 1.85, 95% CI 1.01 to 3.40; P = .048). There were no significant differences between those hearing the public health expert excerpt and the control group (for "yes" relative to "no" RRR = 1.14, 95% CI 0.61 to 2.12; P = .68). These findings suggest that a political speaker's endorsement of the COVID-19 vaccine may increase uptake among those who identify with that speaker. Contrary to highly-publicized focus group findings, our randomized experiment found that an expert's factually accurate message may not be effectual to increase vaccination intentions.