Rep. Bennie Thompson, D-Mississippi, joined Lewis in announcing they won't attending the museum's opening because the president is expected to be there, contending his attendance and "hurtful policies" would be an "insult" to civil rights leaders.
Both the Mississippi Democratic Party and the NAACP chapter in Mississippi said they had not been informed that Trump had been invited by Bryant until it was published in news reports.
"I think this is something that should bring the country together to celebrate the opening of this museum and highlighting [the] civil rights movement and the progress that we've made", she said this week.
"President Trump's statements and policies regarding the protection and enforcement of civil rights have been abysmal, and his attendance is an affront to the veterans of the civil rights movement", Derrick Johnson, NAACP president and CEO, said in a statement released this week.
Numerous seminal moments of the movement - the stories of Emmet Till, of Chaney, Goodman and Schwerner, of Medgar Evers, of James Meredith, of Fannie Lou Hamer and the Freedom Riders and Freedom Summer - all happened on MS soil.
Lewis was one of the original Freedom Riders, a primary organizer of the March on Washington, and famously had his skull fractured while leading a civil rights march in Selma, Alabama in 1965.
On Thursday, former Mississippi Gov. "Donald Trump's words and deeds show he would not stand with people like Medgar Evers, Fannie Lou Hamer, James Chaney, Andrew Goodman, Michael Schwerner and so many, many more". "The majority of the protesters Saturday are going to be the ones who know nothing about what took place back in the day", he said. These icons were witnesses that weeping may endure for a night, but joy will come in the morning.
Others have also announced they are boycotting or protesting. The state spent $90 million on both museums, and another $19 million was privately raised for exhibits and endowments.
"After careful consideration and conversations with church leaders, elected officials, civil rights activists, and many citizens of our congressional districts, we have decided not to attend or participate in the opening of the Mississippi Civil Rights Museum", Lewis said in a statement. "Our hope, indeed our common prayer, is that the Museum will help us move toward individual and collective reconciliation for the hurts, injustices, prejudices, failures, violence and omissions of the past and empower coming generations of Mississippians to do justice and love mercy".