Sen. Susan Collins, R-Maine, said Sunday that she is "not likely" to support former President Donald Trump if he runs again for the White House in 2024.

"Well, certainly, it's not likely given the many other qualified candidates that we have that have expressed interest in running. So it's very unlikely," Collins told host George Stephanopoulos on ABC's "This Week."

"We're a long ways from 2024, but let me say this: I do not think that President Trump should have made that pledge to do pardons. We should let the judicial process proceed. January 6th was a dark day in our history," Collins also said, referencing a comment Trump made about using his presidential power to pardon Jan. 6 rioters during a Save America rally Saturday night in Conroe, Texas.

Former President Donald Trump

CONROE, TX - JANUARY 29: Former President Donald Trump speaks during the 'Save America' rally at the Montgomery County Fairgrounds on January 29, 2022 in Conroe, Texas. Trump's visit was his first Texas MAGA rally since 2019. (Photo by Brandon Bell/Getty Images)

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"If I run and if I win, we will treat those people from Jan. 6 fairly," Trump said of the rioters, many of whom remain imprisoned in Washington, D.C.

"And if it requires pardons, we will give them pardons," he added. "Because they are being treated so unfairly."

Collins wrote in The Washington Post in 2016 that Trump "does not reflect historical Republican values," though she voted to acquit him during his first impeachment trial in 2020. During his second impeachment trial following the Jan. 6 Capitol riot, Collins was one of seven Republican senators who voted to convict him.

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Trump has teased a 2024 presidential bid but has stopped short of formally announcing one. Footage resurfaced last week of Trump saying he would be "the 45th and 47th" President of the United States.

Collins also criticized President Biden for how he has handled the recent vacancy on the Supreme Court following the announcement of Justice Stephen Breyer's upcoming retirement.

Biden

President Biden delivers remarks on the retirement of Supreme Court Associate Justice Stephen Breyer, left, in the Roosevelt Room of the White House in Washington, Thursday, Jan. 27, 2022. (AP Photo/Andrew Harnik)

Biden said Thursday that he will announce his nominee before the end of February, and that the candidate will be a Black woman.

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"I believe that diversity benefits the Supreme Court," Collins said. "But the way that the president has handled this nomination has been clumsy at best." 

"It adds to the further perception that the court is a political institution like Congress when it is not supposed to be," she added.