Christians may belong to whatever political party their conscience can bear. But no Christian can give their highest loyalty to any party, whether Democrat, Republican, Independent, Communist, Green, Lib Dems, Tories, UKIP, or any of the rest.
Our highest loyalty belings to God alone. And to be blunt, if you believe otherwise, your Christianity is highly suspect.
We must serve God rather than man. That is our only real slogan. All the rest verge on paganism.