Republican presidential candidate Rand Paul said Thursday that Bill and Hillary Clinton are "proud" to have presided "over the incarceration of a whole generation of young black men" in comments singling out mass incarceration as "the new Jim Crow."

The senator from Kentucky is an advocate for making changes to the criminal justice system and has co-sponsored legislation with Democratic Sen. Cory Booker to help keep nonviolent criminal offenders out of prison.

"Bill Clinton presided over the incarceration of a whole generation of young black men," Paul said on The Wilkow Majority. "We are putting young black men in jail at a rate never before seen in history and it's because of this war on drugs."

Paul said Hillary and Bill Clinton were "proud to do this."

Hillary Clinton spoke earlier this year of ending "the era of mass incarceration." Clinton's remarks rejected the "tough-on-crime" mantra and legislation advocated by her and her husband during his time as president which included signing the 1994 crime bill.

"And so Hillary Clinton, Bill Clinton, they were all proud to do this," said Paul. "But now that I've been speaking out and saying that mass incarceration is the new Jim Crow, now all of a sudden the Clintons are saying, 'oh wait a minute, we are going to be back on the other side of this issue right now.'"

Paul said Democrats saw him as "a threat to Hillary Clinton" because he goes to communities like Ferguson, Missouri and Baltimore, Maryland and says "what have the Democrats done for you?"

"And I hate to tell you this, but someone from the Democrat National Committee is listening to our radio interview right now and they are looking for ways to attack me, because they see me as a threat to Hillary Clinton, because I'm going to the south side of Chicago, I'm going to the inner city of Philadelphia, I'm going to Baltimore, I'm going to Ferguson, and I'm saying, what have the Democrats done for you? What have they done to alleviate poverty? What have they done for crime? What have they done for the young men in your community and you know why? It's starting to gain traction, and that is why we lead her in several states that Obama won."

Paul said he that understands marijuana isn't good for people, but the law needs to be fair and not incarcerate one race more than another.

"I think that the law needs to be fair and that we shouldn't incarcerate one race more than another and I think the law should be fair in the sense that the penalties should be proportionate to the crime," said Paul.

"You can kill someone in Kentucky and be eligible for parole in 12 years, but we have people in jail for marijuana sales for 55 years, life, 20 years, 25 years. We've gone too far in all of this and then when you add up the numbers, even the white kids and black kids use marijuana at about the same rate and in national surveys the arrests and incarceration rate is four times greater for black males than it is for white males."