GOP frontrunner Donald Trump went after GOP rival Sen. Ted Cruz (R-TX) for missing a Senate vote on a bill that would have audited the Federal Reserve.

“It is so important to audit The Federal Reserve, and yet Ted Cruz missed the vote on the bill that would allow this to be done,” Trump posted on Twitter on Monday afternoon.

It is so important to audit The Federal Reserve, and yet Ted Cruz missed the vote on the bill that would allow this to be done. — Donald J. Trump (@realDonaldTrump) February 22, 2016

Cruz missed a vote on legislation in the Senate that reportedly would have audited the Federal Reserve, as the Guardian noted, as did former Rep. Ron Paul to campaign for his son Sen. Rand Paul (R-KY).

Paul referenced Cruz’s missed vote, previously telling Iowans, “That’s not the type of leadership we need in the White House.”

Ben Jacobs, a reporter for the British newspaper The Guardian, reported Cruz has attempted to gather support from libertarian minded Republicans. “However, by skipping the vote on auditing the Fed, Cruz risks jeopardizing some of the credibility he has built in [the libertarian] faction of the Republican party. Auditing the Federal Reserve has long been an animating cause of Paul and his supporters and it has taken on major symbolic significance,” Jacobs wrote.