WASHINGTON -- The diatribes are as unnerving and unrelenting as they are untrue: An incumbent president warning that the nation's voting systems are cauldrons for fraud and ripe for rigging, seemingly setting the groundwork to discredit the results should he lose in November.
But while such rhetoric lacks precedent in the Oval Office, scholars say it's a familiar playbook that President Donald Trump is using -- and one that has already had a malignant impact on public trust in American democracy.
Trump's repeated warnings of mass robbing of ballots from mailboxes, rampant forgery and flocks of illegal immigrants being permitted to hijack elections have been debunked by voting officials across party lines.
Nevertheless, evidence increasingly shows that Americans are losing faith in the integrity of the nation's elections, putting the U.S. in unaccustomed company.
"I have only ever thought about these things before in an authoritarian setting," said Andrea Kendall-Taylor, a former senior intelligence officer who led the U.S. government's strategic analysis on Russia and is now a senior fellow at the Center for a New American Security, a Washington think tank.
"Now the same indicators are relevant here."
One such indicator comes from a group of academics, called Bright Line Watch, which since 2017 has surveyed Americans on how much confidence they have in the election system. The surveys show a steep drop during Trump's presidency.
When the project began, about 60% of those surveyed said they believed U.S. elections were free of fraud. Now only 45% say they believe that.
A third of Trump supporters surveyed say they would not regard it as undemocratic for a president to attack the legitimacy of election results.
"I am enormously concerned," said John Carey, a Dartmouth professor and co-founder of Bright Line Watch.