When President Joe Biden on Sunday announced that he would step aside as the Democratic presidential nominee and endorsed vice president Kamala Harris as his successor, the historic move opened several floodgates. Among Democrats, one could almost hear an audible sigh of relief; they were finally freed from trying to defend the octogenarian president’s age and mental acuity. Meanwhile, some Republican officials and activists in Texas pounced on the news of a Black woman running for president as an opportunity to engage in thinly veiled racism.In a Sunday social media post, Texas lieutenant governor Dan Patrick, who declined an interview request, wrote that the elevation of Harris represented an effort to secure a “fourth term” for former president Barack Obama. (Patrick also alleged, without evidence,…