But a review of her professional history, as well as interviews with more than a half-dozen lawyers who have worked with her, show that Ms. Ellis, 36, is not the seasoned constitutional law expert she plays on TV.

In many ways, that makes her ideal for the role she has now fashioned for herself: She is a star player in the president’s theater of grievance and denial whose lack of relevant experience with the legal questions at hand has had no apparent bearing on her ability to present herself as someone of great authority.

Since she graduated law school in 2011, nothing in her record in the courtroom — limited mostly to appearances in state court as a prosecutor or as counsel for clients charged with assault, prostitution, theft and domestic abuse — shows any time spent litigating election law cases.

She holds herself out as an expert on the Constitution based on her self-published book and her teaching of pre-law classes to undergraduates. She has never appeared in federal district or circuit court, where most constitutional matters are considered, according to national databases of federal cases, and does not appear to have played a major role in any cases beyond her criminal and civil work in Colorado.