Those in the mix for a potential pardon have ranged from family members and associates all the way to the Tiger King, according to sources.
The growing list is divided into two groups: those being pushed by Trump allies and friends, and requests from individuals serving sentences who aren't necessarily familiar to the president.
The process is not unique to the Trump administration, but some sources say that Trump is prone to subvert the normal procedures when it comes to pardoning, and could announce one-offs as he sees fit rather than waiting until the very end of his term as past presidents have done.
Trump has not fully turned his attention to the growing list of requests, but vetting has already commenced in some cases by White House lawyers, sources say.
One idea that has been floated among Trump allies is the possibility of preemptive pardons for members of the Trump family and close allies of the president.
"The president out the door needs to pardon his whole family and himself because they want this witch hunt to go on in perpetuity, they're so full of rage and insanity against the president," Trump ally and Fox News host Sean Hannity said on his radio program Monday.
White House sources, who describe the talks as preliminary and fluid, say the push for preemptive pardons began early this year around the time of the president's impeachment trial. At that time, the informal conversations -- described by sources as a "series of hypotheticals" -- focused specifically on whether the president could pardon himself. But in recent weeks the idea of preemptive pardons has returned to the Trump orbit, this time including allies and members of his family.
It's not clear how this kind of preemptive pardon would work, given that no member of the Trump family has been accused of a federal crime. However sources pushing for this action say the argument is an "insurance policy" against concerns that the incoming Biden administration could undertake politically motivated investigations. As evidence, sources point to investigations currently being pursued by New York State Attorney General Letitia James and Manhattan District Attorney Cy Vance, both of whom are Democrats.
"The kids have been through enough," said one top adviser who is pushing for the president to issue preemptive pardons for his children.
But sources say Trump has not to this point embraced the idea of preemptive pardons, with some aides concerned that a preemptive pardon could be seen as an admission of guilt of some kind.
The conversations surrounding preemptive pardons have also included Trump allies like the president's personal attorney and former New York City Mayor Rudy Giuliani, whose former associates have been charged by federal prosecutors in the Southern District of New York.
Giuliani, according to sources, has asked the president directly for a preemptive pardon in recent weeks. News of a potential preemptive pardon for Giuliani was first reported Tuesday by the New York Times, after which Giuliani responded on Twitter by calling the story "#fakenews."
The president is well within his authority to issue preemptive pardons, according to legal experts. H. Jefferson Powell, a Duke law professor who previously worked in the Department of Justice's Office of Legal Counsel, told ABC News that the White House has "consistently" taken the position for decades that "the president may pardon even though there has been no conviction."
"A Supreme Court case in 1866 established this," said Michael Waldman, president of the nonpartisan Brennan Center for Justice at New York University. "Two noteworthy examples: President Jimmy Carter pardoned the draft dodgers in 1977 before most had been charged. And of course, President Ford pardoned President Nixon before he was charged" for his actions during the Watergate scandal.
Powell, however, said that preemptive pardons for which the crime is not clear can be "tricky," because they must be specific enough about the conduct in question that a court down the line can determine its scope.
"There is no entire get out of jail free card," Powell said.
There are also no restrictions preventing Trump from pardoning family members, constitutional experts told ABC News, and it has been done before. President Bill Clinton pardoned his half-brother, though it was done after a conviction.
"It might be unseemly, might be a conflict of interest, but I don't know that it would be unconstitutional," said Louis Seidman, a professor at Georgetown who clerked for U.S. Supreme Court Justice Thurgood Marshall.
The president's first postelection pardon, of his first national security adviser, former Lt. Gen. Michael Flynn, has been described by sources as the beginning of a trend. The president is expected to announce more pardons over the coming weeks and will not necessarily wait until his last days in office as former presidents have typically done, sources involved in the deliberations say.
"We've heard from the Tiger King," said one source, who added, "You wouldn't believe the amount of calls, some insane, we've gotten."
"We are waiting on the pen to hit the paper, we think we are very, very close," Eric Love, an attorney for Joseph Maldano-Passage, aka Tiger King Joe Exotic, said about a potential presidential pardon.