Vance’s team approached Emmer, a Republican congressman from Minnesota who has known Walz for years, to aid in the Ohio senator’s debate preparation, the sources said. Emmer has spent the last month studying Walz’s mannerisms and rhetoric to prepare for the role. The New York Times first reported Emmer’s involvement with Vance’s debate preparation.

Crowley, meanwhile, was enlisted by Vance’s team to give the mock debate session as “real and professional” of a feel as possible, the source with direct knowledge of the preparation said. Before serving in the Trump administration, Crowley was a Fox News contributor and occasionally sat in for Sean Hannity on his nightly show.

Vance has been working closely with his top political aides and with senior Trump adviser Jason Miller, who took the lead on the former president’s debate prep, to study for the October 1 showdown. The group has met in person at Vance’s Cincinnati home, as well as on Zoom over the last several weeks, with a focus on helping the Ohio senator better understand Walz stylistically, as well as on familiarizing Vance with Walz’s record as both a Minnesota congressman and governor, the person said.