U.S. President Donald Trump is displaying selective outrage over allegations of sexual harassment against prominent men in politics, but the White House said Friday the allegations he's faced in the past were already adjudicated through last year's election result.

Trump has moved quickly to condemn accusations against Minnesota Democratic Sen. Al Franken as "really bad," but he has remained conspicuously silent on the more serious claims levelled against Roy Moore, the Republican in Alabama's special Senate race who faces allegations he sexually assaulted teenage girls decades ago.

Trump has repeatedly declined to follow Senate majority leader Mitch McConnell and House Speaker Paul Ryan in calling on Moore to quit the race. Both had said they believe Moore's accusers.

With the country confronting revelations of sexual impropriety by powerful men in entertainment and politics, Trump's status as someone accused months before the recent wave of news stories is also a complication for the White House.

More than a dozen allegations of sexual harassment and misconduct were levelled against Trump in the waning days of the 2016 presidential campaign. He was caught on tape in conversation during a Access Hollywood appearance years earlier boasting in graphic detail of sexually harassing women.

This photo was included in Leeann Tweeden's post. (KABC)

Trump has repeatedly dismissed the allegations against him as fake news, most recently telling reporters on Oct. 16: "It's just fake. It's fake. It's made-up stuff."

White House press secretary Sarah Huckabee Sanders said those denials were important.

"Senator Franken has admitted wrongdoing and the president hasn't," she said. "That's a very big distinction."

When asked by a reporter why the allegations against Trump don't require an investigation but Franken's do, Sanders said, "the American people spoke pretty loud and clear when they elected him president."

Franken was accused Thursday of forcibly kissing and groping Leeann Tweeden during a 2006 United Services Organizations tour. Now a Los Angeles radio host, Tweeden released a photo showing the comedian turned senator posing in a joking manner with his hands on her chest as she naps wearing a flak vest aboard a military plane.

In a pair of tweets Thursday night, Trump spotlighted the accusations against Franken, saying the photo "speaks a thousand words."

"Where do his hands go in pictures 2, 3, 4, 5 & 6 while she sleeps?" Trump tweeted. "And to think that just last week he was lecturing anyone who would listen about sexual harassment and respect for women."

Moore has so far been defiant in the face of calls for him to abandon his candidacy. (Brynn Anderson/Associated Press)

Hours before Trump's tweets appeared, Franken moved swiftly to apologize and embrace bipartisan calls for an ethics investigation into his actions.

Tweeden said Friday that in addition to his public statement, Franken personally apologized to her.

In a guest appearance on ABC's The View, Leeann Tweeden read a letter she received from the Democratic lawmaker in which he also discussed the photo in question.

"I have tremendous respect for your work for the USO and I am ashamed that my actions ruined that experience for you. I am so sorry. Sincerely, Al Franken," Tweeden read.

For the second straight day, Tweeden said she wasn't interested in wading into party politics or making a pronouncement on whether Franken should step down.

She said stepping forward wasn't "about donkeys and elephants, this is about right and wrong."

Moore, wife defiant

Trump has not addressed the allegations directed at Moore on Twitter. On Friday, Huckabee Sanders indicated that the White House's previous statements had already dealt with the matter.

Sanders on Thursday declined to say whether Trump believed Moore's accusers, even after the president's daughter, Ivanka Trump, told The Associated Press that she had no reason to doubt their claims against him.

"The president believes that these allegations are troubling and should be taken seriously, and he thinks that the people of Alabama should make the decision on who their next senator should be," Sanders said on Thursday.

Sanders also refused to say whether Trump was pulling his endorsement of the candidate.

Moore has pledged to fight the accusations against him as the state GOP in Alabama reaffirmed its support for the embattled candidate. Two women have come forward by name accusing Moore of initiating sexual contact with them when they were 14 and 16, respectively.

Kayla Moore, wife of former Alabama Chief Justice and U.S. Senate candidate Roy Moore, spoke a press conference on Friday in Montgomery, Ala. (Brynn Anderson/Associated Press)

For the second day in a row, Moore supporters in his home state held a news conference.

"He will not step down," said his wife, Kayla Moore. "He will not stop fighting for the people of Alabama."

She told supporters that Trump actually "owes us a thank you" for taking the media focus off investigations of possible collaboration between his presidential campaign and Russia last year.

As well, Alabama Gov. Kay Ivey said she plans to vote for Moore. She said the state needs to send a Republican to Washington.

Ivey said she has no reason to disbelieve women who have come forward to make allegations of wrongdoing by Moore but said the "timing is a little curious."

On Tuesday, the Republican National Committee pulled its financial support for Moore, following similar action last week by the National Republican Senatorial Committee. The White House said Trump supported the RNC's decision, which came as the party absorbed polling data showing Moore trailing Democrat Doug Jones in the Republican stronghold.

In recent days, GOP officials sought to explain away Trump's refusal to call on Moore to step aside as an effort not to add more fuel to the anti-establishment fires boosting Moore's campaign. They also suggested that Trump was wary of wading into issues of sexual impropriety given the previous claims against him.

But the strike against Franken indicated a more political rationale. The former Saturday Night Live writer and cast member has been an outspoken critic of Trump's administration.