(Reuters) - A Kentucky man accused of attacking U.S. Senator Rand Paul outside his home has agreed to plead guilty to a charge of assaulting a member of Congress, but has told investigators his action was not politically motivated, officials said on Friday.

The Republican Paul’s neighbor, Rene Boucher, 58, was charged with assaulting a member of Congress resulting in personal injury, which is a felony under federal law.

Federal prosecutors will ask a judge to impose a sentence of 21 months in prison in connection with the Nov. 3 attack at a gated community in Bowling Green, Kentucky, court documents showed. Boucher could have faced up to 10 years behind bars.

Paul was wearing headphones while mowing his lawn when Boucher became angered by seeing the 55-year-old senator stack brush near Boucher’s property, the U.S. Department of Justice said in a statement.

Boucher had “had enough” and he ran onto Paul’s yard and tackled him, the statement said, causing Paul to suffer multiple fractured ribs as well as complications that meant he contracted pneumonia.

The attack raised questions about whether Paul had been targeted because of his politics. But Boucher, who like Paul is a physician, told investigators that was not the case, the statement said.

Boucher’s attorney, Matthew Baker, said the pair had a long-standing dispute over property maintenance.

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“Dr. Boucher is a very meticulous sort of fellow,” Baker said. “He continues to be a very regretful and very remorseful. I know that he wishes that it had never happened.”

A spokesman for Paul declined to comment on the federal charge.

Josh Minkler, U.S. Attorney for the Southern District of Indiana, said assaulting a member of Congress was an offense that the authorities take very seriously.

Minkler was assigned to the case following the recusal of the U.S. Attorney’s Office for the western district of Kentucky, where the assault occurred.

No date has been set for the taking of Boucher’s guilty plea and sentencing. Boucher had previously pleaded not guilty to a misdemeanor assault charge that was brought by local prosecutors in Kentucky in connection with the incident.