President Trump, in a moment of levity amid a tense Rose Garden press conference, speculated Monday about what he would be like if he drank alcohol. And, he admitted, the results would not be pretty.

“I can honestly say I’ve never had a beer in my life. It’s one of my only good traits,” Trump told reporters.

"I never had a glass of alcohol. I never had alcohol, for whatever reason," he added. "Can you imagine if I had? What a mess I would be. I would be the world's worst. I never drank, OK?"

Trump was fielding questions from reporters about the newly announced trade deal with Mexico and Canada, when the topic quickly shifted to the FBI investigation of Supreme Court nominee Brett Kavanaugh over sexual misconduct allegations and questions about the judge’s high school drinking.

"I graduated from high school, and while I didn't drink, I saw people drinking,” Trump, a famous teetotaler, said. “They drink beer, go crazy ... Does that mean that they can't do something that they want to do with their lives? It's a very tough thing."

The president has in the past opened up about why he avoids alcohol, citing his brother's struggles.

"I had a brother, Fred – great guy, best-looking guy, best personality, much better than mine,” Trump said last year during a speech about the opioid epidemic. "But he had a problem, he had a problem with alcohol and he would tell me 'don't drink, don't drink.”

Trump said that his brother’s alcoholism, and ultimate death at the age of 43, deterred the president from drinking or smoking.

“He had a very, very tough life because of alcohol,” Trump said. "He was a strong guy but it was a tough, tough thing that he was going through. I learned because of Fred."

Kavanaugh, who has been accused by at least three women of sexual misconduct and drunken behavior, was repeatedly questioned last week about his past alcohol consumption and if he ever “blacked out” from drinking. While the Supreme Court nominee admitted to drinking beer in high school and to continuing to enjoy beer, he said he never “blacked out” and has denied all allegations of sexual misconduct.

Trump said on Monday that he wants the FBI probe into his nominee to wrap up quickly because the accusations have been "so unfair" to Kavanaugh and his family. But he said it's fine with him if the FBI wants to pursue accusations made by three women who have publicly come forward even as he has left the scope of the investigation to Senate Republicans.

In a statement released Sunday, a Yale classmate of Kavanaugh's said he is "deeply troubled by what has been a blatant mischaracterization by Brett himself of his drinking at Yale." Charles "Chad" Ludington, who now teaches at North Carolina State University, said he was a friend of Kavanaugh's at Yale and that Kavanaugh was "a frequent drinker, and a heavy drinker."

"On many occasions I heard Brett slur his words and saw him staggering from alcohol consumption, not all of which was beer. When Brett got drunk, he was often belligerent and aggressive," Ludington said. While saying that youthful drinking should not condemn a person for life, Ludington said he was concerned about Kavanaugh's statements under oath before the Senate Judiciary Committee.

The Associated Press contributed to this report.