Sen. Susan Collins, seen as a possible swing vote in President Trump’s impeachment trial, announced on the Senate floor Tuesday that she will not vote to remove the president. Angus King, Maine’s independent senator, said he will vote to convict the president on both articles of impeachment.

“This decision is not about whether you like or dislike this president – or agree with or oppose his policies – or approve or disapprove of his conduct in other circumstances,” Collins said. “Rather, it is about whether the charges meet the very high constitutional standard of treason, bribery or other high crimes or misdemeanors.”

The Senate is expected to vote Wednesday on the two articles of impeachment against Trump: abuse of power and obstruction of Congress. A two-thirds vote is necessary to remove the president from office, which is seen as unlikely.

In her remarks Tuesday, Collins said it was “improper and demonstrated very poor judgment” for Trump to discuss with the Ukrainian president an investigation into the activity of former Vice President Joe Biden and his son.

However, she argued that the information presented in Article I did not meet the high standard of impeachment or warrant “the extreme step of immediate removal from office.”

Collins also faulted the House, saying it “substituted its own political preference for speed over finality” in failing to go through the judiciary to compel witness testimony and documents.

Collins, who is up for re-election for a fifth term this fall, has been the focus of pressure from both sides throughout the trial, as she had been seen as one of a handful of Republicans who could split from their party to either call for witnesses or remove the president.

In an exclusive interview with “CBS Evening News” anchor Norah O’Donnell Tuesday evening, Collins was asked if she thought she would pay a “political price” in Maine for her vote to acquit.

“I’m sure there are going to be people unhappy with me in Maine. All I can do is apply the constitutional standard and that’s my job,” Collins told O’Donnell. “My job is not to weigh the political consequences, but to do impartial justice, to live up to the oath I took.”

When O’Donnell asked Collins if she thought Trump should apologize to the nation and admit he was wrong in making the phone call to the Ukrainian president, Collins replied, “I think that would be helpful.”

“President Clinton did that in 1999. It took him awhile, but finally he did apologize for his actions,” Collins said.

O’Donnell asked Collins whether she believed Trump would refrain from seeking foreign assistance again.

“I believe that the president has learned from this case. This president has been impeached. That is a pretty big lesson,” Collins said.

O’Donnell pressed Collins by pointing out that the president believes he did nothing wrong. “Why do you think he has learned something?”

Collins replied that Trump’s actions have been criticized by senators from both political parties. “I believe he will be much more cautious in the future,” Collins said.

Later Tuesday evening, The Washington Post reported that Trump, when asked about Collins’ comment that he learned a lesson, told television reporters he’d done nothing wrong, saying, “It was a perfect call.”

In his remarks, King said the president deliberately sought to use his power for his own personal and political interest and undermine the outcome of the 2020 election.

“He has expressed no understanding that he did anything wrong, let alone anything resembling remorse,” King said. “Impeachment is not a punishment, it is a prevention, and the only way, unfortunately, to keep an unrepentant president from repeating his wrongful actions is removal.”

CBS NEWS EXCLUSIVE: Sen. Susan Collins (R-ME) tells @NorahODonnell she will vote to acquit Pres. Trump in the Senate impeachment trial, adding that she believes “the president has learned from this case.”

Watch more tonight at 6:30 p.m. ET. https://t.co/oxGYtYgjBw pic.twitter.com/Wv4PmGINZk

— CBS Evening News (@CBSEveningNews) February 4, 2020

Last week, Collins joined Sen. Mitt Romney of Utah as the only two Republicans to vote to allow new witnesses and evidence in the trial, a motion that was defeated 51-49.

She also was among a small group of Republicans who pushed for the vote on witnesses, calling for the trial to follow the same model as the 1999 Clinton impeachment trial – in which Collins also voted to acquit the president – and for the vote to take place only after opening arguments and a chance for senators to ask questions.

After the vote to allow for witnesses and new evidence failed, Collins voted against her party to support a Democrat-led amendment allowing former National Security Adviser John Bolton to testify, but with her party to table an amendment calling for other witnesses and documents.

Democrats nationally have targeted Collins’ seat in part due to her vote to support Supreme Court Justice Brett Kavanaugh in 2018 and it’s likely her votes on impeachment could influence her re-election campaign.

Reaction to Collins’ plans to acquit the president was swift Tuesday, with the Maine Democratic Party saying in a statement that she “enabled a sham trial” by not pushing harder for witnesses and evidence.

“Mainers demanded a fair trial, but it is clear Sen. Collins was more interested in keeping Mitch McConnell and Donald Trump happy than doing the job that voters elected her to do,” Maine Democratic Party Chair Kathleen Mara said.

“She pretended to call for witnesses and evidence when her vote did not matter,” Gordon Adams, co-director of the progressive Mainers for Accountable Leadership PAC, said in a statement. “And today she has dismissed the corruption of the presidency as a trivial matter.”

Maine Speaker of the House Sara Gideon, a Democrat vying to challenge Collins in November and the leading fundraiser among Collins’ opponents, said in a statement that she would have voted to remove the president.

“Like a lot of Mainers, I believe we needed to hear from relevant witnesses and to consider all evidence as part of this process,” Gideon said. “I also believe that if President Trump was so confident in his innocence then both he and Republicans in the Senate would have gladly allowed that testimony to occur.

“Senator Collins had many opportunities to demand witnesses be included in this trial, but instead she repeatedly blocked that testimony,” Gideon said. “Her decision to acquit despite the case against the president and without hearing more of the facts again reveals her commitment to standing with Mitch McConnell and Donald Trump.”

Staff Writer Dennis Hoey contributed to this story.