Philadelphia District Attorney Larry Krasner's office is not expected to pursue a first-degree-murder charge against the 21-year-old bicycle courier accused of fatally stabbing a city developer near Rittenhouse Square in mid-July, according to a source with knowledge of the decision.

Instead, prosecutors are expected to ask a judge on Wednesday to proceed on counts of third-degree murder, voluntary manslaughter, and possession of an instrument of crime, said the source, who requested anonymity because he was not authorized to speak publicly about the case.

The decision could allow Michael White to be released on bail pending trial, and all but ensures he will not face a life sentence if convicted. The mandatory penalty for defendants convicted of first-degree murder is life without the possibility of parole. A third-degree-murder conviction does not require intent to kill as in first-degree murder, but it still requires malice; the maximum penalty is 20 to 40 years in prison.

Krasner's spokesperson, Ben Waxman, declined to comment on the case Tuesday.

News of the decision came as dozens of relatives, friends, and supporters of White gathered Tuesday evening at a prayer vigil in South Philadelphia and at a simultaneous rally in Center City. They said they hoped — even anticipated — that Krasner would downgrade the most serious murder count against White, who is accused of killing 37-year-old Sean Schellenger, of Point Breeze, during an argument on the 1700 block of Chancellor Street.

Bishop Ernest McNear, speaking Tuesday at the vigil at True Gospel Tabernacle Church at 16th and Mifflin Streets, said that White was in for the "fight of his life," and that he hoped White could soon make bail.

"It's his time now to keep the faith and let this law system work," McNear told about 50 people gathered at the church.

Meanwhile, about 60 more people gathered outside Krasner's office near City Hall to express hope that White would be freed on bail as early as Wednesday.

Sharmina Smith, 20, who described herself as a close friend of White's, said she spoke with him by phone Tuesday.

"He's in high spirits, you guys. He wants to let you guys know that he is so grateful for everyone who is coming out to show support," Smith told those outside the D.A.'s Office.

"He loves you guys, no matter if he knows you or not. He loves you guys."

The two events supporting White highlighted the attention attracted by the incident since it happened July 12. Days later, hundreds gathered to remember Schellenger in the auditorium of Radnor High School, where his father once served as principal.

Attempts to reach Schellenger's relatives for comment Tuesday were unsuccessful.

According to police, White and Schellenger got into a confrontation around 10:50 p.m. White was working as an Uber Eats bicycle courier; Schellenger, who had been dining with friends at Rouge, on Rittenhouse Square at 205 S. 18th St., was with two other men in a Mercedes-Benz when the car became stuck in traffic.

When Schellenger and the others got out of the car and tried to get a driver in front of them to move, police said, White and Schellenger encountered each other and began arguing. The altercation ended when White stabbed Schellenger once in the back and ran away, police said.

Greg Thompson, a White family spokesman, has said that White acted in self-defense because Schellenger — a former quarterback at Pennsylvania State University — tackled him. He also has claimed that Schellenger and the two other men in the car — restaurateur Norris Jordan and entrepreneur Uri Jacobson — were intoxicated and aggressive, allegations that lawyers for Jordan and Jacobson have denied.

"Norris Jordan was not at any point that evening intoxicated," Jordan's lawyer William A. Harvey said Tuesday night. "He was not intoxicated while he was driving, and he was not intoxicated when he was holding his slain friend in his arms. His friend died in his arms."

White was placed in custody after being charged with murder and possession of an instrument of crime.

In a July interview with radio host Solomon Jones, Krasner said the office was still weighing its options.

"Nothing is off the table at this point," he told Jones.

Staff writer Robert Moran contributed to this article.