A political conservative would not.
OK, I buy that for starters as a conflict. I would have said virtually all social conservatives would vehemently believe in preserving the existing definition of marriage, and some political conservatives would not.
Just about the same, but the difference would be those who lean more politically than socially conservative would support preserving the existing definition of marriage, but not necessarily by federal law.
Some political conservatives might not, but no political conservative would support changing it by decree of the federal government.