I think that's why DC isn't a state. DC, unlike PR, has repeatedly shown a willingness to become one, but the republicans won't stand for it. So, ultimately, it isn't a matter of convincing the Commonwealth Party of PR to change its mind, it's a matter of the GOP making enough inroads into the PR community to get some traction there and swing about half their voters to the Dark Side.
DC was never intended to ever become a state. It wasn't even meant to have full time citizens living in it! It was meant for governmental affairs and for those who take care of the buildings and properties to live. They should not be a state.