At some point along the line, Republicans decided that the more someone made liberals angry, the more conservative they were. And now they find themselves defending slavery. The "party of Lincoln".
When the Republican Party first gained traction, many states would have them labeled on the ballots as "Progressive Party".
Teddy Roosevelt ran on a platform of environmental conservation, anti-corruption, anti-monopoly, consumer protections, corporate regulation, social welfare, and income and estate tax.