Jay Sekulow, chief counsel of the American Center for Law and Justice, introduces Republican presidential candidate former Florida governor Jeb Bush during a presidential candidate forum at Regent University in Virginia Beach, Va. (Steve Helber/AP)

The combative lawyer who made the rounds defending President Trump on the Sunday talk shows is not well known to Washington’s criminal defense bar.

A new member of Trump’s legal team, Jay Sekulow, 61, is, however, a fixture on conservative talk radio and a celebrity among conservative organizations for his high-profile First Amendment court battles over religious rights. He has argued a dozen cases before the Supreme Court.

Along with his own widely syndicated daily radio talk show, Jay Sekulow Live! — broadcast on more than 850 radio stations, satellite radio and on his website — Sekulow is also a regular guest on the Fox News Channel, “The 700 Club” and Sean Hannity’s radio show, as well as provides commentary on the Christian Broadcasting Network.

In May, Sekulow dismissed the Russia scandal as “a fraud on the American people.”

On the Sunday shows, Sekulow repeatedly insisted that Trump is not under federal investigation. The Washington Post reported last week that the Russia investigation has widened to include an examination of whether Trump attempted to obstruct justice. But Sekulow said that Trump has not been notified of a probe by special counsel Robert S. Mueller III. He then conceded on “Fox News Sunday” that he doesn’t know for sure if there is an investigation or not.

Sekulow could not be reached for comment.

Nan Aron, president of Alliance for Justice, has often lined up against Sekulow on Supreme Court nominations and other legal issues. Seeing him on television defending Trump, she said, was “totally in keeping with his career.”

“He’s often been the public face of the Republican establishment,” Aron said. “He’s been intimately involved in helping nominees like Samuel Alito and John Roberts get on the court, and it’s safe to say I would fundamentally disagree with his vision of justice, and his views on civil rights, women’s rights and civil liberties.’’

A native of Brooklyn who grew up on Long Island, Sekulow is a self-described Messianic Jew and was a member of the board of the evangelical group Jews for Jesus. He earned his law degree from Mercer University School of Law in Georgia and a PhD from Regent University in Virginia Beach, where he wrote his dissertation on religious influence on Supreme Court justices.

Sekulow started his career as a tax litigator for the Internal Revenue Service. In 1987, Sekulow argued his first Supreme Court case when he represented Jews for Jesus and helped defeat a measure banning the distribution of religious literature at Los Angeles International Airport.

American Lawyer magazine wrote at the time that Sekulow was “rude and aggressive” and “so nervous that at times he appeared nearly out of control.” But for Sekulow, arguing before the Supreme Court was a formative moment, “probably the most intense experience of my life.”

“I left the courtroom feeling like the Beatles must have felt leaving Shea Stadium,” Sekulow wrote in an essay for Jews for Jesus. “Or for those who might not know the Beatles, I felt like Rocky after the fight.” Sekulow won the case in a unanimous decision that struck down the measure.

The victory turned Sekulow into a crusader for religious expressions and a celebrity on the Christian right.

“He is very effective in the courtroom and a very effective advocate with the public,” said Barry Lynn, the lawyer and pastor who leads Americans United for Separation of Church and State and has debated Sekulow more than 100 times in media appearances and on college campuses. “I expect the president will use him frequently because he is a great deal more articulate than the other surrogates.”

Several years after the Jews for Jesus decision, Sekulow became chief counsel for the American Center for Law and Justice (ACLJ), founded by televangelist Pat Robertson and “dedicated to the ideal that religious freedom and freedom of speech are inalienable, God-given rights,” according to the group’s website.

The group has worked against same-sex marriage and in favor of banning abortion. But, ACLJ does not limit itself to religious legal issues. Late last year, ACLJ sued the Justice Department, seeking records of the June meeting at the Phoenix airport between then-Attorney General Loretta E. Lynch and former president Bill Clinton. That tarmac meeting happened about a week before then-FBI Director James B. Comey announced that no charges would be filed in the probe of Hillary Clinton’s use of a private email server.

Despite his lack of experience in criminal defense work, lawyers who know Sekulow hail him as a leader of the religious conservative legal and policy community.

“You definitely should not underestimate his abilities,” said Mat Staver, the former dean of Liberty University Law School who collaborated with Sekulow on several Supreme Court cases. “He is an exceptionally capable and intelligent lawyer who really knows how to win a case,” Staver said. “He is a very rapid-fire thinker and talker. He can get out an argument in one minute that would take two to three minutes for others to make.”

Derek Hawkins contributed to this report.