Joe Biden has acknowledged that his $1.75tn economic and climate legislative package will miss the Christmas deadline for Senate passage and will not pass Congress in the waning weeks of this year.

Negotiations for the president’s Build Back Better bill, for which the Senate Democratic leader, Chuck Schumer, set a Christmas deadline, have stalled as the centrist Democratic senator Joe Manchin of West Virginia has withheld his support for the bill in its current form, making him a key vote in the evenly split Senate.

“My team and I are having ongoing discussions with Senator Manchin; that work will continue next week,” Biden said in a statement on Thursday evening.

“It takes time to finalize these agreements, prepare the legislative changes, and finish all the parliamentary and procedural steps needed to enable a Senate vote. We will advance this work together over the days and weeks ahead,” he added.

Despite the slowed negotiations, Biden reiterated his confidence in the bill’s passing and said that Manchin has signaled in recent discussions his support for the proposal’s general outlines.

“Senator Manchin has reiterated his support for Build Back Better funding at the level of the framework plan I announced in December,” Biden said.

Manchin has expressed criticism of the proposal to continue the expanded child tax credit program through the Build Back Better Act.

While Democrats want to continue the expanded program for one year through the $1.75tn spending package, Manchin has reportedly expressed concern over the cost of doing so. He believes the bill’s programs should be viewed on a 10-year basis when doing costing analysis, even though some of them expire after just a year or a few years.

Should the expanded child tax credit program be extended through the next 10 years, it would require much more funding than the bill allocates.

When asked about Biden and Manchin’s current relationship in a press conference on Friday, the White House press secretary, Jen Psaki, replied: “The president considers Senator Manchin a friend. He’s somebody who he has had many candid and direct conversations with. It doesn’t mean they always agree on everything but that is not the bad that the president sets for his friendships or relationships with members of Congress.”

“He is committed to pressing forward through ups and downs and that’s where we are right now,” Psaki said.

She also added that Biden later on Friday would make a “passionate case” for voting rights legislation that remains stalled in Congress as a result of Republican opposition.

Psaki said of voter suppression attempts going on in several states that: “It’s a sinister combination of voter suppression and election subversion, which is un-American, un-Democratic but not unprecedented.”

And later Friday morning, Biden did speak on the topic when he gave the commencement address at South Carolina State University, a historically Black institution.

He was introduced by Congressman Jim Clyburn, who was instrumental to Biden clinching the Democratic nomination for president last year after he endorsed him when he was trailing in the primaries and swung support in the south and among Black voters.

Biden told the graduating students: “We have to protect that sacred right to vote, for God’s sake,” Biden said. “I’ve never seen anything like the unrelenting assault on the right to vote.”

The president’s comments come as Senate Democrats are discussing potential changes to the filibuster to push voting rights legislation through the evenly divided chamber.

Senate Republicans have used the filibuster to block voting rights legislation, as Democrats do not have the 60 votes necessary to overcome a filibuster.

“This battle is not over. We must pass the Freedom to Vote Act and the John Lewis Voting Rights Act. We must,” Biden told the graduates of the historically Black university.

“We’re going to keep up the fight until we get it done, and you’re going to keep up the fight, and we need your help badly.”