Boucher pleaded guilty to assaulting a member of Congress resulting in personal injury, a felony under federal law.
The recommended sentence is 21 months and a fine.
Paul sustained six broken ribs and bruised lungs in the incident, which stemmed in part over a dispute about landscaping.
"He feels like he has the weight of the world on his shoulders", Baker said.
Special Judge Marianne Battani set Boucher's sentencing for June 15.
Boucher has agreed to pay restitution to Paul in an amount that will be determined at sentencing.
The 59-year-old Boucher has admitted to tackling Paul from behind as he mowed his lawn last November.
Baker said Friday that the attack was a "complete lapse in judgment" by Boucher. An acquaintance of both men said they had long simmering tensions over the way Paul cared for his property and hadn't spoken in years. At the time, he said: "It has nothing to do with politics ... it has to do with a disagreement between two neighbors".
Battani allowed Boucher to remain free on a $25,000 unsecured bond ahead of his sentencing, and ordered him not to have any contact with the senator or his family.
Boucher, a retired doctor and registered Democrat, said the attack was a dispute between neighbors and not politically motivated, according to CBS's Louisville affiliate, WLKY.