Originally Published: 19 JAN 22 11:48 ET

By Clare Foran, Ali Zaslav and Ted Barrett, CNN

(CNN) -- Senate Republicans are expected to once again block a voting bill put forward by Democrats in the latest partisan showdown over voting rights, an issue Democrats are seeking to spotlight despite the fact that they lack the votes to pass the legislation.

The Senate is on track to hold a vote Wednesday evening to attempt to break a GOP filibuster on the legislation, which combines key provisions of two bills: the Freedom to Vote Act and the John Lewis Voting Rights Advancement Act.

At least 10 Republicans would need to vote with Democrats to clear the 60-vote threshold to break a filibuster, which is not expected to happen amid widespread Republican opposition to the voting legislation.

Senate Majority Leader Chuck Schumer has said that if Republicans block the bill, he will hold a vote to change Senate rules to allow for a "talking filibuster" on the voting legislation.

The proposed rules change would force lawmakers who want to filibuster the bill to come to the Senate floor and speak in opposition. Once those speeches come to an end, the Senate would be able to hold a simple majority vote for final passage.

A vote to change the rules has not yet been scheduled but could happen as soon as late Wednesday evening.

But Democrats do not have the votes to change Senate filibuster rules either with moderate Democratic Sens. Joe Manchin of West Virginia and Kyrsten Sinema of Arizona expected to oppose such a move.

Manchin has said he will not vote to eliminate or weaken the filibuster and Sinema has defended the 60-vote threshold. Both senators have argued the filibuster helps bring about bipartisan compromise in the Senate.

As a result, the push to change Senate rules sets up a major showdown among Democrats as the party gears up to put two of its own members on the spot in an effort that appears doomed to fail.

Democrats, who control only 50 seats in the Senate, are under enormous pressure from liberal activists to take action on voting rights and President Joe Biden has trained his focus on the issue as other elements of his domestic agenda remained stalled.

Biden vowed to keep fighting during a recent visit to Capitol Hill but conceded that he doesn't know if Democrats will be able to pass legislation they are pushing for.

"The honest to God answer is I don't know whether we can get this done," Biden said. "I hope we can get this done, but I'm not sure."

Schumer gave an impassioned floor speech on Wednesday and defended the push to change Senate rules.

"As we debate this issue, so critical to the wellspring of our democracy, we will all confront the critical question: Shall members of this chamber do what is necessary to pass these bills and move them to the President's desk? It's my hope that courage awakens within the heart of our Republican colleagues before the day is out," he said, adding that if the Senate cannot protect the right to vote "then the Senate rules must be reformed."

"Our proposal for a talking filibuster on these pieces of legislation would be the first step towards passing voting rights, restoring this body and breaking the gridlock that we now face on this vital issue," Schumer said.