Following the release of Michael Wolff's book "Fire And Fury: Inside the Trump White House," speculation continued to grow about the mental stability of Donald Trump. In response, the president had a few words to say [VIDEO] on the matter.

Trump on Twitter

Ever since Donald Trump announced that he was running for president [VIDEO] back in the summer of 2015, questions were raised as to whether or not he had mental issues. Due to his controversial and unorthodox style, the former host of "The Apprentice" has caused many to question his ability to lead the country as commander in chief. In "Fire and Fury," Michael Wolff claims that many advisers and members of the administration privately doubt that Trump can do the job as president because of questionable mental health.

As expected, this tidbit was quick to dominate the coverage on cable news, much to the chagrin of the billionaire real estate mogul. In response, Trump addressed his mental fitness during a multi-tweet Twitter rant on January 6.

Taking to Twitter on Saturday night, Donald Trump spoke out against those who question his intelligence and mental fitness. Trump accused Democrats of being so desperate that they are now planting doubt in the minds of voters about his state of mind and mental health, claiming that they are doing so because the Russian investigation is not going as well as they had hoped.

The president went on to refer to the Russian investigation as nothing more than a "hoax" that was being reported by the "fake news" in an attempt to take down his administration.

"My two greatest assets have been mental stability and being, like, really smart," Donald Trump went on to write. "Crooked Hillary Clinton also played these cards very hard and, as everyone knows, went down in flames," he continued. "I went from VERY successful businessman, to top T.V. Star to President of the United States (on my first try)," he added. "I think that would qualify as not smart, but genius....and a very stable genius at that!" Trump concluded. This isn't the first time that Trump has gloated about his intelligence, as he's made it a habit to talk big about himself, despite others who continue to push back at his presidency.

Moving forward

The release of "Fire and Fury" has changed the direction of the agenda for the White House, which has been playing defense and been put in damage control mode following the book arrival to the public. While Donald Trump defends himself from allegations of being unfit to the run the country, he hasn't been able to convince many Americans of his argument. After less than a week into the new year, the president has an approval rating that stands at less than 35 percent and is showing no signs of improving anytime soon.