Espy, if elected, would be the first black man or woman elected by Mississippians to Congress since Reconstruction and the first Democrat since 1982.
Mississippi Republican Senator Cindy Hyde-Smith facing criticism for joking about attending a hanging in an online video.
While Cindy Hyde-Smith may be the early favorite going into the election runoff, her campaign may have just taken a hit.
The NAACP also condemned Hyde-Smith's comments, calling a joke about the "barbaric act" "sick".
"If he invited me to a public hanging, I'd be on the front row", Hyde-Smith is heard saying in a video posted to Twitter by journalist and blogger Lamar White Jr Sunday morning (local time).
In a statement, Hyde-Smith said she was merely "accepting an invitation to a speaking engagement".
Hyde-Smith said Sunday it was an "exaggerated expression of regard" for a rancher who invited her to speak and "any attempt to turn this into a negative connotation is ridiculous".
The comment was arguably more problematic given that Hyde-Smith's opponent Mike Espy is the first African-American to win a MS seat in the US House of Representatives since Reconstruction - and would be the first black person to represent the state in the US Senate, if he beats Hyde-Smith.
"There's no excuse to say what she said", White said. Statistics from the NAACP show that almost one-eighth of the nation's 4743 lynchings between 1882 and 1968 took place in Mississippi.
Many critics of Hyde-Smith's comment noted the history of racism and hangings in the state.
The former congressman noted that he sits on the board of directors at the Mississippi Civil Rights Museum and knows "that history very well".
Bryant, who appointed Hyde-Smith, defended her Monday, saying, "There was nothing in her heart of ill will".
If Hyde-Smith wins the election, she will complete the final two years of the term she assumed when she replaced former senator Thad Cochran in March.
Hyde-Smith has received the support of President Trump who tweeted in August that she is "strong" on issues that'll help him "put America first!" They're hurtful to unbelievable Mississippians who are a people of goodwill.
Less than a week into Mississippi's Senate special election election runoff, GOP Sen. "I can tell you all of us in public life have said things on occasion that we could've phrased better".
Another Republican from Mississippi, Trent Lott, lost his position as Senate majority leader in 2002 after saying at the 100th birthday party of SC U.S. Sen.