After months of leading in the 2016 Republican presidential race, Donald Trump has fallen to second place, according to a new national poll released Tuesday.

A CBS News and New York Times poll revealed Ben Carson is now in the lead with a 4-point edge over Trump. Twenty-six percent of Republican primary voters backed the retired neurosurgeon, compared to 22 percent who support the billionaire businessman.

The poll showed Carson won over many key Republican groups, including women and evangelical Christians. He is also performing well with conservatives and the Tea Party base of the Republican Party.

Trump, on the other hand, did well with more moderate Republicans and led Carson among non-college graduates. The two candidates seem to be running neck and neck with men.

However, both candidates still maintain a significant lead over all other GOP contenders. Florida Sen. Marco Rubio came in third place with 8 percent, while former Florida Gov. Jeb Bush and Carly Fiorina are tied in fourth place with 7 percent. All other candidates are at 4 percent or lower.

Last week, a Quinnipiac University Poll revealed that, for the first time, the real estate mogul also fell behind the famed doctor by 8 points among Iowa Republicans. Carson scored 28 percent of voters, while Trump only managed to obtain 20 percent.

During an interview on MSNBC's "Morning Joe" on Tuesday, Trump confessed that he has no idea why he is beginning to slump in the polls.

"Well, I don't get it," he said of Carson's rise in popularity. "You look at different things having to do with Ben and there's a lot of contradiction and a lot of questions. We'll have to see. One thing I know about a front-runner: you get analyzed 15 different ways from China."

The former star of "The Apprentice" went on to say that he would be traveling to Iowa later on Tuesday.

"I'm going there [to Iowa] actually today and I have tremendous crowds and I have tremendous love in the room and, you know, we seem to have hit a chord. But some of these polls coming out, I don't quite get it. "

Trump also took a few jabs at the new GOP front-runner, making note of his record stance on Medicare and abortion.

"You know Ben wants to knock out Medicare. I heard that over the weekend, he wants to abolish Medicare. And I think, you know, abolishing Medicare. I don't think you're going to get away with that one. And it's actually a program that's worked," Trump said.

Although Carson has previously said that he wanted to end traditional Medicare in its current form, he wrote over the weekend in a Facebook question-and-answer post that he would not end the government program.

Trump continued, "Ben, he was pro-abortion not so long ago, as everybody has told me personally. And all of the sudden he's so hard on abortion, under no circumstances, virtually, can there be exceptions."