CANBERRA, Australia -- A former U.S. intelligence official says the Watergate scandal that brought down a president "pales" in comparison with allegations that President Trump's election campaign colluded with Russians.

James Clapper was director of national intelligence until Trump took office in January. He told Australia's National Press Club on Wednesday that the cover-up of a 1972 burglary at the Democratic Party national headquarters in the Watergate complex in Washington that ended Richard Nixon's presidency "was a scary time."

But he says the allegations under multiple investigations of Russian meddling in last year's presidential election are more concerning.

Clapper said: "I think (if) you compare the two that Watergate pales really in my view compared to what we're confronting now."

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Clapper added that some American institutions are under "assault" from the Trump administration.

"So the question is: How long can these assaults go on and the institutions not be irrevocably damaged? I honestly can't say," Clapper said.

Clapper is not the first prominent figure to make the Watergate analogy recently. Last month, following reports that Mr. Trump had asked former FBI Director James Comey to drop an investigation into former national security adviser Michael Flynn, Sen. John McCain, R-Arizona, told CBS News' Bob Schieffer that Mr. Trump's saga of controversy was reaching a "Watergate size and scale."

"The only thing I can say is I think we've seen this movie before, I think it's reaching the point where it's of Watergate size and scale and a couple other scandals you and I have seen, it's a centipede that the shoe continues to drop, and every couple of days there's a new aspect of this really unhappy situation," McCain told Schieffer.

McCain later appeared to walk back his comments, saying he was referring to the administration's managing of the situation, and not the scandal itself.