LOUISVILLE — Neighbors of Republican U.S. Sen. Rand Paul are rallying around their hometown politician days after he suffered broken ribs during what's been called a surprise assault by his next-door neighbor.

It’s still unclear what sparked the incident in the picturesque Rivergreen subdivision in Bowling Green, Ky.

Rene Boucher, 59, a registered Democrat, admitted to going on Paul’s property and tackling him, the warrant alleges. He is charged with fourth-degree assault, a Class A misdemeanor punishable by up to a year in jail and a $500 fine.

The charge is usually reserved for incidents that result in minor injuries. If federal charges are added, Boucher could potentially face 10 years in prison for physically attacking a politician.

His attorney, Matthew J. Baker, entered a not guilty plea on his behalf Thursday morning at an arraignment in Warren District Court.

More:Rand Paul and his neighbor have a history of conflict, says community developer

Boucher has been ordered to stay 1,000 feet away from Paul and his family, unless he is in his own home, which sits a few hundred feet away from Paul's. He's next due in court Nov. 30.

Alicia Stivers, who said she lives in the subdivision and has known the Paul family for nearly 25 years, said Wednesday she has never known Paul to speak unkindly, let alone be physically violent.

“Which makes it all the more shocking that a next-door neighbor of many years who has not so much as exchanged an email or spoken word with Rand or (his wife) in several years, would race downhill and pummel Rand from behind,” Stivers wrote in an email to The (Louisville) Courier-Journal.

Paul suffered six broken ribs and lacerations on his lungs after police say his neighbor, 59-year-old retired doctor Rene Boucher, tackled the politician from behind Friday outside Paul's home, according to an arrest warrant by Kentucky State Police.

Baker has said the “unfortunate occurrence” between the neighbors of more than 17 years “has absolutely nothing to do with either’s politics or political agendas.” He added that it was a “regrettable dispute” over something most people would consider trivial.

More:Mitch McConnell says Rand Paul is expected to be back to work next week

Baker declined to comment Wednesday on a motive, saying only that he’ll be at arraignment and is hopeful there will be no additional criminal charges.

Paul was “blindsided” by the assault, his aides have said in statements to the news media.

Multiple news outlets have reported neighbors’ accounts suggesting some sort of ongoing tension regarding lawn and tree maintenance was at the root of the confrontation.

Travis Creed, who said he is a neighbor and Paul family friend, said the true reason for the “bizarre” attack is known only to Boucher, but he added that reports of a dispute over landscaping or any other topic are incorrect.

“The Pauls are and always have been great neighbors and friends,” Creed wrote in an email. “They take pride in their property and maintain it accordingly. Rand has enjoyed working on and maintaining his lawn for as long as I have known him.”

More:Lawyer: Trivial matter at heart of dispute between neighbor, Rand Paul

Jim Skaggs, who lives close to Paul and developed the gated community back in the 1990s, said Wednesday that he considers both men friends.

Skaggs, a longtime Republican and former chairman of the Warren County (Ky.) Republican Party, said he is closer to Paul, as the two often share political views. Political differences aside, he said, any type of physical confrontation is out of character for both men.

He praised Boucher as an accomplished anesthesiologist and Paul as a talented ophthalmologist who performed successful cataract surgery on both his mother and wife.

More:Rand Paul's doctor neighbor accused of breaking senator's ribs

“I just can’t believe that this happened,” he said. “I’ve been in both these guys’ homes.”

While he said Tuesday that the assault might have stemmed from an ongoing property maintenance issue, Skaggs said Wednesday that he didn’t witness the incident and has heard other possible motives.

“I don’t think any human being would just take off and just attack the neighbor,” Skaggs said.

Paul took to Twitter on Wednesday to thank well-wishers and reveal that an X-ray showed a buildup of fluid around his lungs. Later that night, Paul shared two news articles via Twitter featuring neighbors who disputed the yard maintenance claims.

It’s unclear when Paul will be able to resume his normal work schedule and return to Washington, D.C., where the effort to pass tax reform legislation is atop the GOP to-do list.

Contributing: Thomas Novelly, The (Louisville) Courier-Journal. Follow Matthew Glowicki on Twitter: @MattGlo

More:Sen. Rand Paul assaulted at his Kentucky home, man arrested