Let me begin by saying that I have no problem with DC residents having a congressman. They should have representation in Congress. However, it must be done through the proper means.
Shall we take a little gander through that dusty old document that we call the Constitution? Let's shall.
Article I, Section 2 of the Constitution says this:
The House of Representatives shall be composed of members chosen every second year by the people of the several states, and the electors in each state shall have the qualifications requisite for electors of the most numerous branch of the state legislature.
Whoa! Did you see the clause that I bolded? The most important word there is--you guessed it--STATES. Hmmm...Washington, DC. Seems kind of like a state, right? Wrong! D.C. is a federal district, created under the Constitution (Article I, Section 8 which gives Congress permission to form a "District (not exceeding ten miles square) as may, by cession of particular states, and the acceptance of Congress, become the seat of the government of the United States"). For that simple reason, Washington, D.C. residents do not and, moreover, cannot have the right to federal representation barring admittance as a state or passage of an amendment giving them that right.
This argument is beyond annoying to me, because it shouldn't have to be made. It's one thing to argue about ambiguous constitutional issues (executive privilege, flag burning as speech, abortion). It's another thing for the elected representatives of the people, those same who just swore an oath to uphold the Constitution on Tuesday, to even contemplate something that is on its face unconstitutional.
I've come to expect Democrats to throw out all procedural rules in the Constitution (and before anyone starts snarking, Republicans have their problems, too. They like to conveniently ignore civil protections). But now many Republicans are OK with scrapping the Constitution because it gives Utah an extra seat as well. Yeah, that's statesmanship.