"Trump's attendance and his hurtful policies are an insult to the people portrayed in this civil rights museum".
Lewis said the president's "disparaging comments about women, the disabled, immigrants, and National Football League players disrespect the efforts" of civil rights leaders.
The Mississippi Civil Rights Museum is the only state-sponsored civil rights museum in the country.
Other activists said they will protest Mr Trump's attendance at the event - a move White House Press Secretary Sarah Huckabee Sanders called "very sad".
"The president hopes others will join him in recognizing that the movement was about removing barriers and unifying Americans of all backgrounds", she said. But what was intended as a moment of racial unity and atonement in the state with the largest share of African-Americans is descending into racial and partisan strife after Republican Mississippi Gov. Phil Bryant invited fellow Republican Trump to attend.
The White House expressed disappointment in their decision. Bryant said the president's appearance brings importance to the event. Its exhibits document the history of the civil rights struggle, and the violent white supremacist reaction to it, from 1945 until 1976. "Some of us will stand", says Brice.
Mr. Lewis, who voted on Wednesday in favor of a failed attempt to begin impeachment proceedings against Mr. Trump, has clashed with the president several times since he won the election.
Another person not happy about President Trump's visit is Jackson City Councilman Melvin Priester.
Brice has another perspective, "I think that the Governor's inclusion of Donald Trump to this occasion was a political stunt".
The national NAACP also disapproved of the invitation.
Jeff Steinberg is the founder of the Sojourn to the Past, a program that educates children about the Civil Rights movement, and is attending the opening Saturday. The museum's website states that the opening celebration "is open to all and will include music, speakers, and food trucks". "We are kinder and more tolerant here in MS than I think perhaps other places".
"I can not express my gratitude enough to those heroes and "she-roes" who are being honored in our museum", she said.
That's right: The president thinks it's unfortunate that Lewis would not honor the sacrifice made by civil right leaders such as, well, Lewis.