Rafael Montero’s comeback attempt with the Mets this season could be finished.

The right-hander had a “setback” during his rehab appearance for Single-A St. Lucie on Sunday, according to general manager Sandy Alderson, and is back to “Square One” in his rehabilitation.

“I wouldn’t count on him helping us this year,” Alderson said Monday.

Montero has been on the disabled list since April 30 after complaining of soreness in his right shoulder.

Though subsequent tests revealed no structural damage, Montero has complained about discomfort at various points this summer, leading to stops and starts in his rehab.