The Democrats should do it anyway, along with Puerto Rico and Guam. If Washington citizens have to pay income taxes, they should also chose two senators and representatives.
Puerto Rico and Guam don't pay federal taxes. They are also colonial holdings with a very different history acquisition than the US. DC residents also don't pay full taxes, since their local government is subsidized by the federal government.
DC residents pay federal income taxes though, that should be enough.
The other two should be admitted for other reasons.
