A 53-year-old man with rectal cancer starting at 2 cm from anorectal ring presents to the office to discuss further management. He has undergone chemoradiation and consolidation FOLFOX chemotherapy for cT3N1aM0 microsatellite proficient tumor. He has a partial response with a residual palpable mass. He normally has up to five bowel movements per day with urgency and fecal leakage. What is the best next surgical treatment for him?