President Donald Trump is alleging that the Department of Justice put a "spy" inside his presidential campaign as part of an effort to frame him for crimes he says "didn’t commit."

"'Apparently the DOJ put a Spy in the Trump Campaign. This has never been done before and by any means necessary, they are out to frame Donald Trump for crimes he didn't commit,'" Trump tweeted Friday, quoting Fox Business Network anchor David Asman. "Really bad stuff!"

“Apparently the DOJ put a Spy in the Trump Campaign. This has never been done before and by any means necessary, they are out to frame Donald Trump for crimes he didn’t commit.” David Asman @LouDobbs @GreggJarrett Really bad stuff! — Donald J. Trump (@realDonaldTrump) May 18, 2018

Later, the president weighed in again, saying that if the reports are true, it would be the "all time biggest political scandal."

Reports are there was indeed at least one FBI representative implanted, for political purposes, into my campaign for president. It took place very early on, and long before the phony Russia Hoax became a “hot” Fake News story. If true - all time biggest political scandal! — Donald J. Trump (@realDonaldTrump) May 18, 2018

Rudy Giuliani, one of Trump's lawyers, said on Friday that the president's legal team had been told about an informant "off the record," but added that he didn't know if the information was correct.

"I don't know for sure, nor does the president, if there really was one," Giuliani said on CNN. "For a long time we've been told by people that there was some kind of infiltration."

Trump's tweet Friday was the second time in as many days that the president has claimed the government put a "spy" inside his campaign.

On Thursday — the anniversary of the appointment of special counsel Robert Mueller — Trump tweeted that then-President Barack Obama had "spied on the Trump campaign," an apparent reference to an allegation by Andrew McCarthy, a former federal prosecutor and assistant U.S. attorney, made Thursday on Fox News.

"Wow, word seems to be coming out that the Obama FBI 'SPIED ON THE TRUMP CAMPAIGN WITH AN EMBEDDED INFORMANT,'" Trump tweeted Thursday. "Andrew McCarthy says, 'There's probably no doubt that they had at least one confidential informant in the campaign.'

"If so, this is bigger than Watergate!" the president added.

Wow, word seems to be coming out that the Obama FBI “SPIED ON THE TRUMP CAMPAIGN WITH AN EMBEDDED INFORMANT.” Andrew McCarthy says, “There’s probably no doubt that they had at least one confidential informant in the campaign.” If so, this is bigger than Watergate! — Donald J. Trump (@realDonaldTrump) May 17, 2018

McCarthy said on Fox News, "I've written a couple of columns in the last week or so pointing out that there's probably no doubt that they had at least one confidential informant in the campaign."

In an article in The National Review on May 12, McCarthy questioned whether the FBI had used a "human source" inside the Trump campaign in an attempt to confirm elements of the Steele Dossier, a 35-page document compiled by former British intelligence agent Christopher Steele that contained lurid allegations about Trump.

The publication of the dossier, by Buzzfeed in January 2017, helped fuel speculation on Trump's connections to Russia.