On the day that the man accused of assaulting Rand Paul pleaded not guilty, the senator's chief strategist called the attack a "blindside" by a "disturbed person."

"This is a serious criminal matter involving serious injury, and is being handled by local and federal authorities," Paul strategist Doug Stafford said in a statement. "As to reports of a longstanding dispute with the attacker, the Pauls have had no conversations with him in many years."

Stafford continued that the first "conversation" between Paul and the person who allegedly assaulted him, Rene Boucher, happened after Paul's ribs were broken.

"This was not a 'fight,' it was a blindside, violent attack by a disturbed person," Stafford said. "Anyone claiming otherwise is simply uninformed or seeking media attention."

Boucher, 59, pleaded not guilty to a misdemeanor charge on Thursday. He has been ordered to stay 1,000 feet away from Paul and his family.

Senate Majority Leader Mitch McConnell said Tuesday that Paul, who has five broken ribs, will return to work next week.

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Contributing: Eliza Collins, USA TODAY; Thomas Novelly, Louisville Courier Journal