Billy Baldwin, 54, blasted Donald Trump on Thursday accusing him of trying to come onto his wife two decades ago at a party hosted at the-then property mogul's hotel.

Billy, brother to actors Alec and Stephen Baldwin, tweeted at Donald Trump Jr. accusing his father of being inappropriate with his wife, Chynna Phillips, over two decades ago.

He was replying to Trump Jr.'s tweet about Sen Al Franken which said: 'Talk amongst yourselves: Two more women accuse Sen Al Franken of inappropriate touching.'

Billy Baldwin (pictured second from left in 1993), 54, blasted Donald Trump (right) on Thursday with an incriminating tweet, accusing him of being inappropriate toward his wife

Unsurprisingly his words sent the Twittersphere into a frenzy, including Billy.

Billy's response said: 'Your Dad is a 5th degree black belt when it comes to sexual impropriety allegations. In fact… I once had a party at the Plaza Hotel… your father showed up uninvited & hit on my wife… invited her on his helicopter to Atlantic City.'

'She showed his fat ass the door. #TrumpRussia,' he ended it with.

Billy, brother to actors Alec and Stephen Baldwin, tweeted at Donald Trump Jr. (pictured above) accusing his father of being inappropriate with his wife over two decades ago

One user commented on the conversation: 'I know you are not very bright, but here is a hint, when your father is the holy grail of sexual abuse, dont go around posting about others. avoiding the topic is your better option.'

Another social media user boldly wrote: 'Unlike your father supporting a child molester, we Democrats will eventually expel Franken.'

Billy has clearly never been a Trump fan if his Twitter profile is anything to go by.

His cover photo on Twitter is a picture of several of the past US Presidents, including Barack Obama, George Bush and Bill Clinton - with notable absence from Trump.

Billy was praised for his comments against the President by Twitter (pictured above)

A man who attended the party told the Daily News that Baldwin was hosting an intimate get-together in a Plaza hotel room for his soon-to-be wife Chynna Phillips' birthday when Trump suddenly ambushed.

'Trump came barging in and started saying, "Let's get in my helicopter, let's blow this party and get out of here,"' the party attendant recalled.

The source added that everyone was uncomfortable by his presence especially as it was such an intimate gathering with only about five people in the room.

Billy Baldwin is pictured here with his wife Chynna Phillips, they've been married since 1995

Trump then zeroed in on Phillips and 'looked her up and down,' he continued.

'He tried to coerce her into getting in his helicopter,' he said. '(Phillips) laughed uncomfortably at the prospect and said thanks but no thanks.'

Allegations of sexual misconduct against Trump arose during the 2016 presidential campaign.

On October 7, 2016 a video was released where then presidential candidate Trump and television host Billy Bush were engaging in a very lewd conversation about women.

Trump pictured here Thursday was accused of several sexual assault during the 2016 presidential campaign

In the video Trump said: 'I did try and f*** her. She was married. I moved on her very heavily. I moved on her like a b****. But I couldn’t get there. And she was married. Then all of a sudden I see her, she’s now got the big phony t*** and everything. She’s totally changed her look.'

'I better use some Tic Tacs just in case I start kissing her. You know, I’m automatically attracted to beautiful — I just start kissing them. It’s like a magnet. Just kiss. I don’t even wait. And when you’re a star, they let you do it. You can do anything.'

The most famous line from their crude conversation was when Trump said: 'Grab ’em by the p****. You can do anything.'