HARRISBURG — A note apparently hand-delivered to the home mailbox of Gov. Tom Wolf’s nominee for Pennsylvania State Police commissioner has raised the issue of race in one of the nation’s largest police forces.

The handwritten note arrived in Col. Marcus Brown’s suburban Harrisburg mailbox on Monday night amid an increasingly ugly battle over Brown’s nomination to lead the state police.

It said: “No (racial epithet) lover will wear my uniform.” It was signed “didnt-dont,” an apparent reference to criticism by retired troopers of Brown’s decision to wear the state police uniform despite not having graduated from the State Police Academy, as every trooper must.

Brown, a former Baltimore police officer and superintendent of the Maryland State Police, has touted his commitment to recruiting minorities into the police force. He also has drawn criticism from retired state troopers after his suggestion last September following turmoil in Ferguson, Mo., over the fatal shooting of an unarmed black man that the militarization of police escalates civil disobedience.

Brown, who is acting commissioner, gave the note to local police, and says it does not reflect the character of the Pennsylvania State Police he has met.

In light of the note, a top Senate Democrat wrote to Wolf on Wednesday to urge him to stand behind Brown.

Sen. Vincent Hughes, D-Philadelphia, said Wednesday the letter is unacceptable and he tied it to Brown’s commitment to recruiting minorities. It is of particular concern because the percentage of nonwhite Pennsylvania state troopers has dropped to 6 percent from 20 percent in 1999, Hughes said.

Brown’s nomination is before the Republican-controlled state Senate for confirmation. No vote is scheduled, and Brown can continue to run the agency as its acting commissioner without confirmation.

Opposition to Brown’s nomination drew greater media attention after police began investigating a claim last week that he was caught on video removing two roadside signs criticizing him for wearing the uniform. The signs were put there by a retired state trooper from Western Pennsylvania who says his free speech rights were violated.

Brown apologized, but the troopers’ union and top Senate Republicans called on Wolf to withdraw Brown’s nomination. Wolf has refused.

A Senate Republican spokesman said, “The note has nothing to do with the concerns we have over the decisions that Col. Brown has made and the pattern of poor judgment he has displayed.” Those concerns include the shutdown of a busy Maryland highway last year during a manhunt.