Near the end of the convention, Gerry, Randolph, and Mason emerged as the main force of opposition. Their fears were increased as the Convention moved from Madison's vague Virginia Plan to the concrete plan of Rutledge's Committee of Detail. Some have argued that Randolph's attacks on the Constitution were motivated by political ambition, in particular his anticipation of possibly facing rival Patrick Henry in a future election. The main objection of the three was the compromise that would allow Congress to pass "navigation acts" with a simple majority in exchange for strengthened slave provisions. Among their other objections was an opposition to the office of vice president.