The only way to make it Constitutional is to pass a Constitutional amendment. It's a bit ironic that Orrin Hatch belongs to a church, one of whose prophets said that its priesthood leaders would be part of the group that saves the Constitution from destruction, but he uses a specious argument to unmask his impatience at getting Utah a fourth seat in the House of Representatives and further diluting the meaning of the Constitution.
Hatch noted that Congress has opted to collect federal taxes from D.C. residents and allows the federal court to have jurisdiction over the district, even though the Constitution says these actions are allowed for "states."
"The question is whether the fact that the District is not a state trumps Congress' legislative authority," Hatch said. "Congressional action and judicial precedent throughout American history suggest that the answer is no."
The 23rd Amendment to the Constitution made it so that the District of Columbia could choose electors for President and Vice President. I'm not sure, then, if it took an amendment for that, how it wouldn't require a similar amendment to allow DC to have a representative in Congress.
I heard the other morning that some people think that anyone who disagrees that DC should get a representative is a racist, because most DC residents are black. Hmmm. Constitution be damned. Course I've been accused of being a racist before by people who don't understand that three/fifths thingy in the Constitution.
I've also heard it said that this is a balanced, non-political solution--to give the most republican state in the Union a Republican seat and DC a surely democratic seat. In reality, this is the most political "solution" I can think of. How it can be considered a solution, I'm not sure. The only two non-political solutions are (1) be patient until the next census, and (2) amend the Constitution.
Utah will most assuredly get another seat in the US House as a result of the next census. Orrin Hatch needs to be put out to pasture. If he's leading the vanguard of further ignoring the constitution, he needs to be defeated in his next election.