Alan Dershowitz, Ken Starr and Robert Ray joining Trump impeachment trial legal team

Dershowitz says he'll speak in the president's defense on the Senate floor.

Former independent counsels Ken Starr and Robert Ray are expected to join President Donald Trump's Senate impeachment trial legal team, a source familiar with the plan told ABC News Friday.

Former Harvard Law School professor Alan Dershowitz, a constitutional expert, is joining the team as well, his office confirmed in a statement noting that he will help argue in the president's defense on the Senate floor.

"Professor Dershowitz will present oral arguments at the Senate trial to address the constitutional arguments against impeachment and removal.," the statement said. "While Professor Dershowitz is non partisan when it comes to the Constitution—he opposed the impeachment of President Bill Clinton and voted for Hillary Clinton— he believes the issues at stake go to the heart of our enduring Constitution. He is participating in this impeachment trial to defend the integrity of the Constitution and to prevent the creation of a dangerous constitutional precedent."

Separately, a senior administration official confirmed that Starr, Ray and Dershowitz will be part of the president's team. All three have appeared frequently on Fox News criticizing the impeachment effort and expected to present parts of Trump's case to the Senate.

Starr was a central player in the impeachment case against President Bill Clinton and both Starr and Dershowitz were involved in Jeffrey Epstein's defense.

Ray succeeded Starr and is currently a white collar criminal defense attorney in New York.

Dershowitz wrote a book called "The Case Against Impeaching Trump."

Starr is a former federal appeals court judge who in 2016 resigned as chancellor of Baylor University, after being demoted as president of the school amid criticism of the way the school handled accusations of sexual assault by football players.

White House counsel Pat Cipollone and one of the president's personal lawyers, Jay Sekulow, will still be leading the defense, according to the source.

The White House has yet to publicly announce the president's team but the developments come ahead of opening arguments in the trial scheduled to begin Tuesday.

Former Florida Attorney General Pam Bondi, who was brought into the White House to deal with impeachment messaging, is also expected to join the defense team, according to sources.

Jane Raskin, one of the president's outside personal attorneys who represented him during the Mueller probe, is also expected to join, sources said.

Asked for his reaction to not being included on the president’s defense team, one of the the president's personal lawyers, Rudy Giuliani, told ABC News that's “excellent” because he’s a potential witness.

What role Republican House members such as Rep. Jim Jordan of Ohio might play was still unclear but it was not expected that they would appear before the Senate.

ABC News' Jordyn Phelps and Julia Jacobo contributed to this report.