The truth is taking a back seat to false claims in the U.S. election campaign because journalists can’t keep up, according to an American political science professor.

University of Pennsylvania professor Kathleen Hall Jamieson says Donald Trump, Bernie Sanders and Hillary Clinton aren’t being held as accountable as they should be, because journalists aren’t knowledgeable enough to catch them when they make untrue statements on the campaign trail. Politicians also have a broader range of media outlets to speak to than ever before, meaning they can “go place to place and deceive,” Hall Jamieson told CTV’s Canada AM on Tuesday.

And while Republican presidential nominee Trump might claim the media is aligned against him, he’s actually getting away with a lot.

“The media are challenging him occasionally, but they’re not challenging him often enough to catch up with the facts that are distorting his record,” Hall Jamieson said.

Hall Jamieson runs the website, which attempts to keep up with all the claims politicians make on the campaign trail. But while she tries to hold Trump and his opponents to the facts, Trump has been claiming on a regular basis that journalists are aligned against him.

She said a number of Trump’s claims have been untrue, but he hasn’t been taken to task on enough of them. For instance, Hall Jamieson refuted Trump’s claims that there were Muslims cheering in New Jersey after 9-11, and pointed out that the judge adjudicating a case against Trump in California is not Mexican, despite Trump’s claim. Additionally, she highlighted the fact that Trump has incorrectly suggested there is a link between vaccines and autism – an incorrect bit of misinformation that has been repeatedly proven false.

But Trump isn’t the only one presenting misinformation on the campaign trail. Hall Jamieson says many politicians routinely exaggerate problems, which makes it tough to evaluate whether their solutions are appropriate.

“We can’t really determine what the problems are if we don’t agree on the facts,” Hall Jamieson said.

“For example, (Democratic presidential candidate) Bernie Sanders is saying that people are working longer hours for lower pay. Well actually they’re working longer hours but they’re being paid more. So if we’re going to talk about income inequality, we need to diagnose the problem in order to determine the solution.”

Hall Jamieson also suggests part of the problem is that the public, particularly in the U.S., has lost some of its trust in institutions, including journalism, so fewer people are paying attention when someone challenges a politician.

“The voices of authority are having more difficulty correcting when misinformation is out there,” she said.

Hall Jamieson says it’s not an easy societal problem to address, but the way to fix it is through education.

“Teach people how to understand what evidence is, why we should trust sources of authority and when we should be skeptical of them,” she said.