On May 29, 1787, the "Virginia Plan" was proposed to the Constitutional Convention advocating for a national government with three branches - legislative, executive, and judicial. From the article:
"On Tuesday, May 29, Virginian Edmund Randolph introduced the fifteen resolutions of the Virginia Plan. This plan proposed an independent executive, a national judiciary, and a bicameral Congress. Representation would be proportional to population in both houses. The plan also included a national veto over state laws to prevent injustice in the states. Finally, it proposed to send the work of the convention to popular ratifying conventions in the states rather than to state legislatures. Madison knew the Virginia Plan went beyond Congress’s instructions merely to revise the Articles, so he wanted the people’s representatives to approve it. He wanted to avoid the state legislatures, however, suspecting they would oppose the plan’s strengthening of the national government at the expense of their own governments."