But Trump, who regularly trades in rumor and innuendo, touted anonymous sources in a very prominent way several years ago when he was pushing the "birther" theory against the president and to attack him on other fronts.
Interestingly, the tweet about the president's birth certificate being a "fraud" came more than a year after Obama took the extraordinary step of releasing his long-form document from the state of Hawaii.
Trump pushed the birther theory for years -- even claiming to send investigators to Hawaii -- only backing down on Sept. 16, 2016.
"President Barack Obama was born in the United States period," he said that day. The admission came just a day after an interview with the Washington Post in which he refused to acknowledge the president's natural-born citizenship.
Trump is also fond of the suggestive "many people are saying" or "people are saying."
For instance, on Aug. 8, he tweeted:
Factcheck.org, a non-partisan, nonprofit organization, called the claim "baseless."