A 32-year-old man is brought to the emergency department following a motor vehicle accident with severe blunt abdominal trauma. On arrival, he is hypotensive (BP 80/50 mmHg), tachycardic (HR 128/min), and in hemorrhagic shock. Two large-bore IV lines are established. After initiating rapid crystalloid infusion, what is the drug of choice for ongoing hemodynamic support if the patient remains hypotensive despite adequate fluid resuscitation?