There are many special interests lurking within the Democratic Party, but each and every one of them wants something from government - they want government to do something for them, and/or against someone else... whatever their motivation doesn't matter. They want to wield government for their own ends.
Most Republicans are the same as every Democrat - only with different special interests to cater to. That said, what libertarians there are in Washington, they do reside in the Republican Party; but they are so few in number as to be inconsequential.
The one thing that the core of both the Republican and Democratic Parties have in common is that neither has any use for the rule of law. The Constitution means nothing to the majority of both parties - just as it means nothing to most Americans.