A 46-year-old man with long-standing hypertension and type 2 diabetes has chronic kidney disease with an eGFR of 32 mL/min/1.73 m2 and albumin-to-creatinine ratio of 450 mg/g. He is on lisinopril, amlodipine, and atorvastatin. BP is 132/78 mm Hg. Potassium is 4.8 mEq/L. What is the most appropriate next step to slow progression of his kidney disease?