If Abraham Lincoln prioritized Federalism over States' Rights and freed the slaves, how is he a Conservative?

Ditto on the first answer. "Liberal" and "Conservative" have criss-crossed between "Democrat" and "Republican" more than once over the past 2 centuries, and there have been times when you'd find liberal and conservatives in both parties at the same time. Increasingly over the past half-century the Republican party has been ideologically purifying itself to allow for only right-wingers and conservatives.