Why are Republicans (but not Democrats) in favor of TAXATION WITHOUT REPRESENTATION for citizens in D.C.?

Republicans oppose D.C. having representation because the population is heavily comprised of African Americans who overwhelmingly vote Democrat. About 53% of D.C.'s population is African American. (a href="http://www.fedstats.gov/qf/states/11000.html)" rel="nofollow"http://www.fedstats.gov/qf/states/11000.…/a AND something like 90% of all African American voters vote Democrat. This is just another Republican ploy to oppress a minority of people who would vote against them.