The Heartland Institute study tried to gauge the probable impact that fraudulent mail-in ballots cast for both then-candidate Joe Biden and his opponent, President Donald Trump, would have had on the overall 2020 election results.

The study was based on data obtained from a Heartland/Rasmussen survey in December that revealed that roughly one in five mail-in voters admitted to potentially fraudulent actions in the presidential election.

After the researchers carried out additional analyses of the data, they concluded that mail-in ballot fraud "significantly" impacted the 2020 presidential election.

They also found that, absent the huge expansion of mail-in ballots during the pandemic, which was often done without legislative approval, President Trump would most likely have won.

"Had the 2020 election been conducted like every national election has been over the past two centuries, wherein the vast majority of voters cast ballots in-person rather than by mail, Donald Trump would have almost certainly been re-elected," the report's authors wrote.

Over 43 percent of 2020 votes were cast by mail, the highest percentage in U.S. history.

'Biggest Story of the Year'

The new study examined raw data from the December survey carried out jointly between Heartland Institute and Rasmussen Reports, which tried to assess the level of fraudulent voting that took place in 2020.

The December survey, which President Trump called "the biggest story of the year," suggested that roughly 20 percent of mail-in voters engaged in at least one potentially fraudulent action in the 2020 election, such as voting in a state where they're no longer permanent residents.