"We're talking about that as we speak," Padres manager Bud Black said.
Richard has a 2-5 record and a 7.01 ERA in 11 games, including 10 starts.
The Padres could turn to someone from their bullpen, like long relievers Tim Stauffer or Tyson Ross. Stauffer has made 70 starts in his career, but only one in 2012.
Ross began the season as the Padres' fifth starter, making three starts before he got injured. He was 0-1 with a 3.86 ERA. He has been working on retooling his swing since suffering a subluxation of his left shoulder swinging the bat in April.
The Padres could also turn to the Minors and starter Robbie Erlin, who started Friday, the same day as Richard. Erlin made his Major League debut out of the bullpen earlier this season for the Padres, before making a June 1 start against Toronto. He allowed two runs in 6 2/3 innings.
"In a few days, we'll have to make a few decisions on our roster," Black said.
Jamal Collier is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.