During the American Reconstruction of 1867-76, African-American men participated in Georgia politics for the very first time. Newly freed by the Emancipation Proclamation and given their civil rights under the Fourteenth Amendment, they were now able to vote and stand for public office.
The new state of affairs enraged Southern Democrats. They regarded African Americans as racially inferior; as far as they were concerned, black people shouldn't even have been freed from slavery, let alone granted civil rights.
In 1868, the white majority in the Georgia State Legislature voted to expel African-American legislators, the original 33 members who had recently been elected. Strange as it may seem, most of the black delegates to the state's post-war constitutional convention actually voted against including in the state constitution the right of black legislators to hold office.
The white majority in the Georgia State legislature cynically picked up on this vote to justify their actions in expelling the so-called "Original 33". But in actual fact they were motivated more than anything else by racial prejudice. They didn't believe that African Americans were capable of participating in government, and in any case didn't want to serve alongside them. Due to the Supreme Court of Georgia ruling in White v. Clements (1870), however, the legislature's decision was overturned and the black legislators were reinstated.