The residents of Washington, DC have never been full citizens under the law. It is possible to find a way to give them full voting rights and full representation in Congress without violating the mandates of the Constitution, while avoiding the problems that have caused proposed Constitutional amendments to fail.
There is no evidence, nor any reasonable presumption, that the Framers and / or Founders intended to deprive legal residents of their rights of citizenship, while protecting Federal governance of Government institutions in the District of Columbia.
Therefore, bipartisan legislation should be created, with White House sponsorship, which would be acceptable to members of Congress to accomplish these goals.