Jenna Ellis, a senior legal adviser to the Trump campaign, is not the type of lawyer she plays on TV.

Jenna Ellis broke into the legal profession in 2012 as a deputy district attorney in Weld County, Colo., a largely rural area that would soon make headlines for a failed attempt to secede from the rest of the state because some residents resented the growing dominance of more liberal communities to the south like Denver. Ms. Ellis prosecuted crimes like theft and assault, felonies of a different magnitude from the claims of sweeping fraud and criminal conspiracy she makes today as a top lawyer to President Trump.

It wasn’t long before she parlayed her law degree and experience as a prosecutor into jobs that thrust her beyond her corner of the state: She took a position with James Dobson, the evangelical heavyweight, joined the faculty at Colorado Christian University and started appearing on Denver radio as a legal commentator.

By late 2018, regular viewers of cable news would come to know Ms. Ellis as a “constitutional law attorney” — her preferred title — who aggressively came to Mr. Trump’s defense as he faced investigation and impeachment.

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.

On paper, the Trump campaign calls her a senior legal adviser. She has recently appeared alongside Rudolph W. Giuliani and other Trump lawyers — a group Ms. Ellis described as an “elite strike force team” — at public hearings where she amplified the president’s false claims of widespread voter fraud.

In a written statement responding to questions about her record, Ms. Ellis described herself as “a highly experienced and highly qualified attorney and expert in my field.” Any assertions to the contrary “cast me in a false light,” she said. The Trump campaign provided the name of one federal case in which it said Ms. Ellis had participated, in 2012, when she was a year out of law school. But her name is not among the lawyers listed in the decision, and the case was not heard in a regular federal court, but rather in an administrative tribunal.