Democrats support D.C. statehood. Democrats have the votes (once Massachusetts names its new Senator) to made "New Columbia" the 51st state. D.C. statehood would cure an injustice. D.C. statehood would be a partisan move...but no more partisan than the creation of two Dakotas in the 19th century, and far more justified on the democratic principle of representation.
Democrats should pass D.C. statehood.
(The form of statehood that is possible with 60 votes in the Senate is the "cutout" option, in which the Capitol, the Supreme Court, the White House, the National Mall, the adjacent federal buildings, and virtually no actually residents become the Constitutionally described District for the Seat of the Government of the United States, while the remainder of the current district becomes a state).
If Republicans want to complain about that, let them. It will be no better or worse than complaints about death panels and czars and whatever other nonsense that Rush and Glenn Beck are spouting. The odds that statehood would be the issue that pushes voters in Arkansas or Montana or Louisiana over the edge seems awful small to me, and it's hard to believe that the GOP base would get unduly riled up over it beyond how upset they are about the rest of the Democratic agenda.
The Democrats have been pushing a bill to give the District a vote in the House; the bill passed the Senate earlier this year but stalled because the Senate added an amendment on guns that House liberals opposed. Frankly, I have no idea why Democrats settled for the House vote; the cutout option is clearly (as far as I can tell) constitutional. The biggest obstacle is that two Senate Democrats opposed the representation bill. I have no idea whether those two, Byrd and liberal fave Max Baucus, would oppose cloture on a statehood bill, but then again the two Maine Republicans voted for the bill, and might support statehood as well. Meanwhile, if the price is forcing New Columbia to include a strong 2nd Amendment type provision in their state constitution, I'd hope that they would be willing to do that. I'd also recommend that Democrats leave in the extra House seat for Utah that was part of the representation bill: why not? Hell, I'd figure out a way to give the Republicans an offset House seat for the next decade, if it meant that the handful that supported the representation bill would support statehood. No offset, of course, in the Senate.