Independent presidential candidate Robert F. Kennedy Jr. on Tuesday doubled down on his suggestion that President Joe Biden is a greater threat to democracy than former President Donald Trump because of what Kennedy claimed was the Biden administration's censoring of political speech online.

Kennedy, a former Democrat, appeared on Fox News' "Fox & Friends" where he was asked to expand on a recent comment of his that Biden is arguably a "much worse threat to democracy."

"I said I can make that argument, and I think it's an argument that we ought to be having," Kennedy responded.

He then seemingly cited a case currently before the U.S. Supreme Court over claims that federal officials had engaged in a "broad pressure campaign" to censor certain viewpoints related to the COVID-19 pandemic and the 2020 election.

In one example at the center of that dispute, a White House official sent an email to a Twitter staffer after a post from Kennedy suggested, without evidence, that baseball legend Hank Aaron had died from the COVID-19 vaccine.

The White House has argued that its contact with the companies has been aimed at protecting public health, national security and election integrity and has never involved threats of adverse consequences. The private companies have said publicly that they can and do moderate content as they wish.

During oral arguments before the high court last month, a majority of justices signaled they did not believe the Biden administration had gone too far.

But Kennedy on Tuesday took a darker view of the government's actions -- seeking to blame Biden directly.

"President Biden has done something that no other president in the history has done, which is to order media, particularly the social media -- Facebook, Twitter, Instagram, YouTube, Google -- to censor his political opponents,” Kennedy alleged.

He warned of the "undermining" of the First Amendment.

"I think, you know, what President Trump said about, you know, questioning the election and, you know, to the extent that he engaged in an effort to overthrow that, of course that's a threat to democracy. But it is not the worst threat," he said.

The Biden campaign declined to comment on Kennedy's latest criticism, but national Democrats have been increasingly attacking Kennedy and seeking to tie him to Trump.

“He is an extremist, he is not in the mainstream of this country," Democratic National Committee Chair Jaime Harrison said on CNN last week. Democratic spokesperson Matt Corridoni also slammed Kennedy in a previous statement as a "stalking horse" for Tump, which Kennedy rejects.

"We're facing an unprecedented election and we know the GOP is already working to prop up third party candidates like Robert Kennedy Jr.," Corridoni said.

Kennedy, on Fox, also repeated his umbrage at being denied Secret Service protection despite earlier requests.

ABC News previously reached out to the Department of Homeland Security about why Kennedy was denied protection and the agency declined to comment.

Such decisions are made in consultation with an advisory panel that includes congressional leaders.

The Secret Service's website lays out several factors that the DHS and the committee consider in whether to assign a candidate a protective detail, including but not limited to a Real Clear Politics national polling average of 15% or greater for over 30 days, a risk assessment conducted by the agency and the level of campaigning that is occurring nationally.

The Secret Service is legally required to protect presidential and vice-presidential candidates and their families 120 days out from a general election -- a measure taken in response to the 1968 assassination of Kennedy's father, Robert F. Kennedy, while campaigning for the Democratic nomination.

The younger Kennedy has repeatedly requested Secret Service protection beyond the private security he already employs.

Appearing on CNN on Monday, Kennedy complained about his lack of a Secret Service detail, which he linked to what he called Biden's more troubling habit of using power compared to Trump.

"I think that is a threat to democracy -- him [Trump] trying to overthrow the election clearly is a threat to democracy," Kennedy said. "But the question was: Who is worse threat to democracy? And what I would say ... I'm not going to answer that question, but I can argue that President Biden is."

He pointed to the importance of the First Amendment in the eyes of the founding fathers.

"We put the guarantee of freedom of expression in the First Amendment because all of our other constitutional rights depend on it. If you have a government that can silence its opponent, it has license for any atrocity," he said.

ABC News' Luke Barr, Devin Dwyer, Nicholas Kerr and Brittany Shepherd contributed to this report.