Anthony Johnstone has posted this draft on SSRN. Here is the abstract:

The Constitution’s Guarantee Clause provides “The United States shall guarantee to every State in this Union a Republican Form of Government.” At a time of national political division and dysfunction the Union, as well as the Republican Form of Government itself, would be better served by letting states do more, and the United States less, to fulfill this guarantee. States do and should play as important a role as the federal government in articulating and implementing the law governing state political processes, or in formal terms, their republican forms of government. This article provides a reminder that the Guarantee Clause defines state governments by the indefinite article.

The argument has four parts. Part I introduces the basic meaning of the guarantee and its evolution through the voting rights amendments. Beyond a consensus that holds our republicanism to require basic political equality, various perfectionist conceptions of a republican form of government diverge, reflecting the essential pluralism of republican governments in a federal system. Part II explains how the Supreme Court, Congress, and the Executive are now unable to articulate, let alone implement, any workable consensus on republicanism beyond a thin conception of those basic rights. Part III describes the states as the source of persistent and important distinctions in their republican forms of government, as both legal systems and political cultures that produce and are sustained by those systems. Part IV argues these distinctions in how states articulate and implement their own versions of republicanism are crucial to efforts toward reforming republicanism at the national level. Given the unsettled visions of republicanism at the national level, and the structural autonomy the states must retain at the core of our federal system, a plurality of views on republicanism among the states is not only durable but desirable.