Since January, PolitiFact has rated 52 percent of Republicans' statements as mostly or entirely false, compared to just 24 percent of Democrats' statements, the study found. In the first three weeks of May, amid controversies over the attacks in Benghazi, Libya and investigations at the Internal Revenue Service and the Department Of Justice, 60 percent of Republicans' statements were rated as false, compared to 29 percent of those made by Democrats.
George Mason University's Center for Media and Public Affairs, which conducted the study, looked at 100 claims, 46 made by Democrats and 54 by Republicans.
Rep. Michele Bachmann's (R-Minn.) claim that the IRS runs a "huge national database" of personal details, for instance, got a "pants on fire" rating.
“While Republicans see a credibility gap in the Obama administration, PolitiFact rates Republicans as the less credible party,” George Mason University CMPA president Robert Lichter wrote in a release with the Tuesday report.
The center released similar findings last year when it compared the Obama and Romney campaigns, giving Obama higher marks on truthfulness.
The study is far from a scientific referendum on partisan honesty -- as PolitiFact's editor Bill Adair noted, the statements it chooses to check aren't a representative sample of what either party is saying.
Adair wrote in an email to Poynter's Andrew Beaujon that statements are selected on the basis of news judgment.
"PolitiFact rates the factual accuracy of specific claims; we do not seek to measure which party tells more falsehoods," he told Beaujon. “The authors of this press release seem to have counted up a small number of our Truth-O-Meter ratings over a few months, and then drew their own conclusions.”
PolitiFact itself is no stranger to controversy, often from both sides of the aisle. The site annually causes chagrin with its "Lie of the Year" award. It gave that designation to Mitt Romney's Jeep ad in 2012, and to the claim that Republicans voted to end Medicare in 2011, earning an "avalanche of criticism" for the latter.