Christopher Scalia, the son of the late Supreme Court Justice Antonin Scalia, told Fox News Wednesday that the idea of increasing the number of justices on the high court is "maybe an argument worth taking seriously," but added that some proposals by Democratic candidates were "just unconstitutional."

Scalia took particular issue with an idea advanced by South Bend, Ind., Mayor Pete Buttigieg in which the Supreme Court would have 15 members, five of whom would "only be seated by unanimous agreement of the other 10," as Buttigieg told "Fox News Sunday."

"The problem with that," Scalia told "Your World with Neil Cavuto" Wednesday, "is, obviously Section 2, Article II of the Constitution makes very clear that the president has the power and authority to nominate and, with the advice and consent of the Senate, to appoint Supreme Court justices. So, I mean, I don't know what ... these candidates are talking about, but they certainly can't have justices appoint their colleagues. So, that would require an [constitutional] amendment that I just don't think has a snowball's chance anywhere of being ratified."

Buttigieg is not the only Democratic candidate who has raised the prospect of overhauling the Supreme Court if they win the White House. Other 2020 contenders, including Sens.Cory Booker, Elizabeth Warren, Kamala Harris, and Kirsten Gillibrand have mused about adding seats to the court or, in Booker's case, implementing term limits on what has traditionally been a lifetime appointment.

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Scalia said the proposals echo Franklin D. Roosevelt's "court-packing" scheme from the 1930s, which the 32nd president eventually abandoned.

Despite that, Scalia argued that FDR's proposal "did have an effect. It kind of intimidated a Supreme Court – or so, kind of the conventional wisdom goes – into being more amenable to what he was trying to do with the New Deal.

"So, he didn’t get more justices, but he did get a lot of what he wanted done, done," he added. "And it’s possible that the Democrats, just by raising this threat of packing the court are trying to do something similar."

The Constitution does not enshrine a set number of Supreme Court justices; that is up to Congress. The number of justices has been set at nine since 1869, but the tally has been as low and six and as high as ten.

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Scalia said that the latest proposals by Democrats are the latest step in a political war over the judiciary that has lasted for nearly two decades.

"This goes back to the early 2000s when Democrats filibustered a lot of President Bush’s nominees and Republicans responded in kind by filibustering a lot of Obama’s nominees, and so the Democrats responded by ending the filibuster for lower court nominees, and then Republicans when the Democrats filibustered [Neil] Gorsuch, Republicans got rid of the filibuster for Supreme Court nominees," he said. "It goes on and on. So, if the Democrats try to do this, try to pack the court, I don’t know why they’re under the impression that the next time they have the Senate and the next time they have the president, Republicans will never be in power again because they’re on the right side of history and history will finally meet its ultimate end."

Fox News' Bill Mears contributed to this report.