Sexual misconduct by powerful men has all but taken over the news, with Sen. Al Franken, D-Minn., Rep. John Conyers Jr., D-Mich., and senatorial hopeful Roy Moore, R-Ala., among the politicians on this growing list.

President Donald Trump vociferously has taken aim at accused Democrats, while apparently giving a pass to Republicans. Moreover, it was only a year ago that similar accusations against Trump dominated the headlines, with more than a dozen women accusing Trump of improper conduct or sexual assault. Many of the accusations surfaced after the release of a 2005 tape of Trump speaking graphically about kissing and groping women uninvited.

During the second presidential debate, Anderson Cooper asked then-candidate Trump point blank whether he had "actually kiss(ed) women without consent or grope(d) women without consent?" Trump asserted that "nobody has more respect for women" and Cooper pushed him, asking, "Have you ever done those things?" Trump denied that he had, responding: "No, I have not."

The president has held this line, telling the New York Times, when asked the same question: "I don't do it. I don't do it."

But it's not as simple as that. Many of the women have produced witnesses who say they heard about these incidents when they happened — long before Trump's political aspirations were known. Three have produced at least two witnesses.

Such contemporaneous accounts are essential to establishing the credibility of the allegation because they reduce the chance that a person is making up a story for political purposes. In the case of sexual allegations, such accounts can help bolster the credibility of the "she said" side of the equation. Often, a sexual assault will occur behind closed doors. The contemporary corroborators can explain what they heard at the time and whether the story being told now is consistent with how the story was told years earlier. This does not necessarily mean an allegation is true, but it does give journalistic organizations more confidence to report on the allegation.

The Washington Post Fact Checker first detailed some of the accusations against Trump during the 2016 campaign. That fact check also detailed the witnesses who backed up claims of sexual accusations against former president Bill Clinton — who, like Trump, insisted the women accusing him were not telling the truth.

Here's a list of 13 women who have publicly come forward with claims that Trump had physically touched them inappropriately in some way, and the witnesses they provided. We did not include claims that were made only through Facebook posts or other social media, or in lawsuits that subsequently were withdrawn.

We also did not include the accounts of former beauty contestants who say Trump walked in on them when they were half nude because there were no allegations of touching. Trump had bragged on the Howard Stern show of his "inspections" during the pageants: "You know they're standing there with no clothes. Is everybody OK? And you see these incredible looking women. And so I sort of get away with things like that."

Two or more contemporary corroborators

Natasha Stoynoff

Allegation: While she was interviewing Trump in 2005 for an article for People magazine about the first anniversary of his third marriage, Trump lured her into a room at Mar-a-Lago, forced her against a wall and abruptly kissed her, forcing his tongue into her mouth. He then said they were going to have an affair.

Corroborators: Marina Grasic, who has known Stoynoff for more than 25 years. She said she got a call from her friend the day after the alleged attack, detailing exactly how Trump pushed Stoynoff against a wall.

Liz McNeil, at the time a reporter for People (she is now an editor). She said that she heard about the incident the day after Stoynoff returned from her assignment. "She was very upset and told me how he shoved her against a wall," she said.

Mary Green, another People reporter (now editor) who had just returned to New York. "In an early conversation we had in her office, she told me about what happened with Donald Trump," Green said. "She was shaky, sitting at her desk, relaying that, 'He took me to this other room, and when we stepped inside, he pushed me against a wall and stuck his tongue down my throat. Melania was upstairs and could have walked in at any time.' "

Liza Hamm, part of a "tight-knit' group of friends. "Natasha has always been a vivacious person who wants to believe in the best of people, and this experience definitely messed with that outlook," she said.

Paul McLaughlin, Stoynoff's former journalism professor. He said Stoynoff called him at the time of the alleged incident seeking advice on how to handle it: "She didn't know what to do, she was very conflicted, she was angry, she was really confused about how to deal with this." After a discussion, he said, Stoynoff decided it would be best if she kept the incident to herself.

Response: Anthony Senecal, Trump's former butler, denied the incident: "No, that never happened. Come on, that's just bull crap." Trump said: "Why didn't she do this 12 years ago? She's a liar. . . . It never happened. It's a lie."

Rachel Crooks

Allegation: Trump in 2005 kissed her directly on the lips after she introduced herself and said she was a receptionist who worked for a company that did business with Trump.

Corroborators: Brianne Webb, her sister. She said Crooks called her about the incident as soon as she returned to her desk. "Being from a town of 1,600 people, being naive, I was like, 'Are you sure he didn't just miss trying to kiss you on the cheek?' She said, 'No, he kissed me on the mouth.' I was like, 'That is not normal.' "

Clint Hackenburg, her boyfriend at the time. After he asked her that evening how her day had gone, "she paused for a second, and then started hysterically crying."

Response: Shouting at the New York Times reporter who called for comment, Trump said, "None of this ever took place." He then told the reporter, "You are a disgusting human being."

Cathy Heller

Allegation: While having Mother's Day brunch at Mar-a-Lago in 1997 or 1998, her mother-in-law introduced her to Trump. She extended her hand to greet him and he grabbed her and kissed her on the mouth. She did turn her head slightly and so he wasn't able to "get my whole mouth."

Corroborators: Lloyd Heller, her husband. He said that she immediately told him. He said he told her that "you should have punched him" and he remembers being "puzzled" by why Trump would do something like that in a public space.

A relative who was there, but wanted to stay unnamed. This person said Heller was immediately shocked and asked whether he or she had seen what happened. The two then talked about the incident asking, "Who does he think he is?"

Response: Trump campaign spokesman Jason Miller told People Magazine: "There is no way that something like this would have happened in a public place on Mother's Day at Mr. Trump's resort."

One contemporary corroborator, one additional witness

Kristin Anderson

Allegation: While she was at a Manhattan nightclub in the early 1990s, Trump slid his fingers under her miniskirt, moved up her inner thigh and touched her vagina through her underwear.

Corroborators: Kelly Stedman, a friend. She said she was told about the incident at a women's brunch a few days later. The women found themselves "laughing at how pathetic it was" on Trump's part.

Brad Trent, a New York photographer. He says he heard the story from Anderson at a dinner in 2007. "It was just girls saying stories about how they got hit on by creepy old guys," Trent said of the conversation around the table.

Response: The Trump campaign, in an emailed statement, said Anderson had fabricated the story: "Mr. Trump strongly denies this phony allegation by someone looking to get some free publicity. It is totally ridiculous."

One corroborator

Summer Zervos

Allegation: Trump kissed Zervos on the lips when he met her in his New York office, which upset Zervos, who had been a contestant on Season 5 of Trump's "The Apprentice." She then met Trump at the Beverly Hills Hotel in 2007 for what she thought would be dinner; instead, she was escorted to his private bungalow. "I stood up and he came to me and started kissing me open-mouthed as he was pulling me toward him," she said. "He then grabbed my shoulder and started kissing me again very aggressively and placed his hand on my breast." He kept pursuing her, she said, at one point "thrusting his genitals" against her as he tried to kiss her. She said she again rebuffed him.

Corroborator: Ann Russo, friend: She said that Zervos told her in 2010 that Trump had been "verbally, physically, and sexually aggressive with her" but that she had rebuffed his advances. "It was apparent she was conflicted with what Mr. Trump had done to her," she said, adding that Zervos was torn between her admiration for Trump and Trump's behavior.

(In her lawsuit against Trump, Zervos says that in 2007 she "spoke to a friend and her parents about (the initial kiss), all of whom concluded that this must just be the way that Mr. Trump greeted people." She then told her father about the hotel incident, the lawsuit says.)

Response: Trump issued a statement by John Barry, a cousin of Zervos's: "I think Summer wishes she could still be on reality TV, and in an effort to get that back she's saying all of these negative things about Mr. Trump. That's not how she talked about him before. I can only imagine that Summer's actions today are nothing more than an attempt to regain the spotlight at Mr. Trump's expense, and I don't think it reflects well."

Mindy McGillivray

Allegation: McGillivray said she was groped by Trump at Mar-a-Lago in 2003, when she was 23, at a photo shoot during a concert by Ray Charles. "All of a sudden I felt a grab, a little nudge. I think it's Ken's camera bag, that was my first instinct. I turn around and there's Donald. He sort of looked away quickly. I quickly turned back, facing Ray Charles, and I'm stunned." She told the Palm Beach Post she was certain it was not an accident. "This was a pretty good nudge. More of a grab," she said. "It was pretty close to the center of my butt. I was startled. I jumped."

Corroborator: Ken Davidoff, photographer: He vividly remembers when McGillivray pulled him aside moments after the alleged incident and told him, "Donald just grabbed my ass!" He did not witness the incident himself.

Jill Harth

Allegation: In the early 1990s, Jill Harth and her boyfriend at the time, George Houraney, worked with Trump on a beauty pageant in Atlantic City, and later accused Trump of inappropriate behavior toward Harth during their business dealings. She said that Trump pursued her and groped her; she alleged attempted rape in a sexual harassment suit that was withdrawn as a condition for settling a contract dispute. (We are including her account here because she gave interviews making these charges even after the lawsuit was withdrawn.) Trump had "his hands all over me," Harth told the New York Times. "He was trying to kiss me. I was freaking out."

Corroborator: George Houraney, her boyfriend and later husband. The two are divorced but he confirmed her account in an interview with Nicholas Kristof: "Houraney and Harth haven't spoken in years, but they offered almost identical accounts when I interviewed them separately, and their stories match Harth's deposition and her sexual harassment lawsuit from the time."

Response: Trump said it was Harth who had pursued him, and his office shared email messages in which Harth thanked Trump for helping her personally and professionally. The campaign said she was a "pawn" in a lawsuit created by her ex-husband.

Jessica Leeds

Allegation: Trump attacked her while seated next to her on an airline flight. More than three decades ago, when she was a traveling business executive at a paper company, Leeds told the New York Times in 2016, she sat beside Trump in the first-class cabin of a flight to New York. They had never met before. About 45 minutes after takeoff, Trump lifted the armrest and began to touch her. Trump grabbed her breasts and tried to put his hand up her skirt. "He was like an octopus," Leeds said. "His hands were everywhere." She fled to the back of the plane. "It was an assault," she said.

Corroborator: Leeds told the story to at least four people close to her, who also spoke with the New York Times. But most appear to have heard about it more recently. Linda Ross, a neighbor and friend, heard about it six months before Leeds went public, for instance.

Reaction: The Trump campaign offered the perspective of a British man who claimed to have sat near the two on the plane and three decades later remembered the incident in detail. "She was the one being flirtatious," he said.

Other accusers

Temple Taggart McDowell: The 1997 Miss Utah USA said Trump kissed her directly on the lips, at a time he was married to Marla Maples and McDowell was 21. Later, when she visited Trump Tower to discuss a modeling contract, she says Trump again embraced and kissed her on the lips, this time in front of two pageant chaperones and a receptionist. The New York encounter made one of the chaperones so "uncomfortable" that she advised McDowell not to go into any rooms with Trump alone, McDowell told NBC News.

Karena Virginia: A yoga instructor said Trump harassed and groped her during a chance encounter at the U.S. Open in 1998. Virginia said Trump, a total stranger, then grabbed her arm and touched her breast. "I was in shock," Virginia said. "I flinched. He said, 'Don't you know who I am?' I felt intimidated and powerless. I said 'yes.'"

Jennifer Murphy: A former Apprentice contestant said Trump in 2004 kissed her on the lips. "He walked me to the elevator, and I said goodbye. I was thinking 'oh, he's going to hug me,' but . . . he pulled my face in and gave me a smooch."

Ninni Laaksonen:A former Miss Finland said Trump in 2006 grabbed her bottom shortly after he had married Melania. "Trump stood right next to me and suddenly he squeezed my butt. He really grabbed my butt."

Jessica Drake: A porn star and sex educator said that during a 2006 golf tournament in Lake Tahoe, Trump "grabbed" her and two other unnamed women tightly and kissed them on the lips "without asking permission." He then offered Drake $10,000 and the use of his private plane, she said, if she would agree to come back to his room and accompany him to a party.