Carlos Moore is the attorney for Joshua Blunt, 25, of Grenada, who is set to make an initial court appearance Tuesday.
Moore said city prosecutor Jennifer Adams told him she would reduce Blunt's charge to culpable negligence, which is punishable by a maximum one year in prison. The maximum penalty for second-degree murder is life in prison.
Adams told The Associated Press that she will release a statement about the case Tuesday.
Blunt's daughter, Shania Caradine, died Thursday. She was the second Mississippi child to die in a hot car within two weeks. No charges have been brought against a parent in the other case.
Blunt was booked into the Grenada County Jail early Friday and remained there Monday under a $250,000 bond. Moore said he will ask a city judge to either reduce or remove the bond so Blunt could be released. Moore also said he will fight the reduced charge.
"He made a mistake," Moore said. "It was a tragic mistake. It was a fatal mistake. But it was an accident."
Blunt went to work at a restaurant Thursday morning, then took a break to pick up his girlfriend and their baby, Moore said. Blunt took his girlfriend to work at a fast-food restaurant and was supposed to drop off the baby at his girlfriend's mother's house.
"He intended to take the child to the grandmother's house, but somehow he forgot," Moore said.
Blunt went back to work for about four hours, and when he and a colleague went to his car, the colleague discovered the unresponsive baby in the back seat, Moore said. They took Shania inside the restaurant and put cool towels on her to await an ambulance that took her to attorneys the University of Mississippi Medical Center Grenada. Grenada County Deputy Coroner Jo Morman said physicians at the hospital tried unsuccessfully for hours to revive the baby.
Janette Fennell, founder and president of the Kansas-based KidsAndCars.Org, said that between 1990 and 2015, charges were brought in 45.5 percent of cases involving the deaths of children in hot cars in the U.S., and no charges were brought in 44.5 percent of cases. It was unknown if charges were brought in the remaining 10 percent of cases, she said.
The group's figures show there were 706 cases of children dying in hot cars for those 25 years, although some cases involved multiple deaths.
Using a slightly shorter set of years, from 1990 to 2014, Fennell said there were 726 deaths of children in hot cars in the U.S.
"This topic has no income level, no race, no religion," Fennell said. "It can happen to absolutely anyone."
She said some people are quick to say parents who leave children in hot cars are monsters.
"It really has to do with the way our memory lets us down," Fennell said.
Moore questioned why Blunt, who is African-American, faces charges while the white mother who left her child in a car in another county has not been charged.
"The million-dollar question is: What is the difference in the two scenarios?" Moore said. "The only difference I see is race, and that's sad."
Grenada Assistant Police Chief George Douglas said in a separate interview that race was "most definitely not a consideration."
"We did not investigate, nor did we charge, in this case as relates to race," Douglas said.
KidsAndCars.Org does not keep track of race in its tracking of hot car deaths because that information is "really, really hard to find," Fennell said.