WASHINGTON, D.C. – U.S. Senator Marsha Blackburn (R-Tenn.) spoke out against the Democrats’ efforts to institute an unconstitutional overhaul of the electoral system.

Republican Sen. Marsha Blackburn slammed the Democrats’ sweeping election reform bill, saying the left "has launched an assault on having free and fair elections," warning ahead of the vote Tuesday that it will be "difficult" for Republicans to get on board.

"They are advocating policies that are going to result in removing the ability of state and counties to manage their own elections," Blackburn, R-Tenn., told Fox News Tuesday.

"One of the issues we have is the way local election officials have responded to this," Blackburn explained. "The bill is taking away their ability to run those elections."

Blackburn told Fox News that prior to being elected to the Senate, and the Tennessee State Senate, she served on Williamson County's election commission.

"That is something you take as a very, very serious opportunity because it is your responsibility to be certain those rolls are cleaned up, be certain volunteers and poll workers and properly trained, that everyone knows the rules, and that ballots are counted and resulted and made available, and that it is all done in a transparent manner," Blackburn said.

She added: "One person, one vote. Every legal vote to be counted. Those are the foundation for our electoral process."

Blackburn noted that "the more people know about this bill, the less they like it."

The For the People Act, also known as S.1, is the largest overhaul of U.S. election law in at least a generation and covers many aspects of the voting process, including requiring states to automatically register eligible voters and offer same-day voter registration.

The bill would massively expand the role of the federal government in how states run their elections. It also requires states to offer 15 days of early voting and allows no-excuse absentee balloting, which 14 states would have to implement. The states that already allow it would have to conform to S.1’s standards.

Sen. Joe Manchin, D-W.Va., a moderate Democrat, said over the weekend he would vote against his colleagues on the legislation, calling the measure too partisan.

"It's the wrong piece of legislation to bring our country together and unite our country, and I'm not supporting that because I think it would divide us more. I don't want to be in a country that's divided any further," Manchin said on "Fox News Sunday."

Manchin and Sen. Kyrsten Sinema, D-Ariz., another moderate Democrat, are facing pressure to support the voting reform bill.

The House of Representatives passed the House version of the legislation, H.R. 1, in March by a vote of 220 to 210. No Republicans joined with Democrats in approving the sweeping voter rights reform.