Wisconsin Republican Gov. Scott Walker on Thursday called Barack Obama “the biggest liar of the world,” in reference to the former Democratic president’s infamous claim that people could keep their health care plans under ObamaCare.

Walker, locked in a tight re-election battle with Democratic challenger Tony Evers, made the comments during a campaign speech in Waukesha with House Speaker Paul Ryan at his side.

Referencing how Wisconsin Democrats brought Obama in to rally voters last week, Walker mentioned how Politifact in 2013 rated Obama’s claim about keeping their health care its “lie of the year.”

“So, I guess if you’re going to lie about health care and pre-existing conditions, you might as well bring in the biggest liar of the world,” Walker said.

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Video of Walker’s comments were posted on social media.

Campaigning in Wisconsin last week, Obama called Walker a liar over his campaign ads on health care.

“Your governor has been running an ad during election time saying he is going to protect pre-existing conditions when he is literally doing the opposite,” Obama said. “That is some kind of gall. That is some kind of chutzpah. But let’s also call it what it is. It is a lie.”

The Fox News Gubernatorial Power Rankings lists the Wisconsin governor’s race as “lean Democrat,” with most polls showing Walker trailing. But a Marquette University Law School Poll released Wednesday shows the contest at a dead heat, with Walker and Evers tied at 47 percent.