Council members said they were disgusted by Councilman Jim Motznik's backroom politicking in the weeks leading up to O'Connor's death from cancer, the Pittsburgh Tribune-Review reported.
The council voted 7-1 to elect Motznik's political rival, Doug Shields, to succeed Luke Ravenstahl as council president, the newspaper said.
"The mayor was in his final hours, and this was not a good time to be lobbying for any votes for anything," said Councilwoman Tonya Payne.
The newspaper said Shields declined to comment on Motznik's snubbing.
"I only hope that I can live up to Mayor Bob O'Connor and the example that he set," Shields said.