Trump's point here is that (he believes that) the members of the Democratic party are not behaving in a way so as to support the primary meaning of "democratic", which is

relating to or supporting democracy or its principles.
_{(definition via Google)}

Instead, he implies, it is now acting primarily to advance the well-being of its own members.

In other words, he is saying that the Democratic Party is a party for supporting Democrats, not a party for supporting democracy.

Trump's point here is that (he believes that) the members of the Democratic party are not behaving in a way so as to support the primary meaning of "democratic", which is

relating to or supporting democracy or its principles.
_{(definition via Oxford)}

Instead, he implies, it is now acting primarily to advance the well-being of its own members.

In other words, he is saying that the Democratic Party is a party for supporting Democrats, not a party for supporting democracy.