Jennifer Rubin: Kamala Harris is in, and she’ll be a formidable challenger

Nearly five decades after Shirley Chisholm announced her run as the first African American woman to seek the Democratic nomination for president, Sen. Kamala Harris, D-Calif., declared her run for president with an appearance on ABC’s “Good Morning America” and a slick video:The Democratic presidential field is already crowded with two female senators (Kirsten Gillibrand of New York and Elizabeth Warren of Massachusetts), former San Antonio mayor Julián Castro and two le