Senate Majority Leader Chuck Schumer told Democratic colleagues Monday that this legislative session has led to moments of "deep discontent and frustration" as the Build Back Better Act hangs in limbo, blaming Sen. Joe Manchin, D-W.Va., for not coming "to an agreement" with President Biden, while maintaining that the caucus will continue to "try to find a way forward" on the president’s economic agenda.

In a letter to Democratic colleagues Monday morning, Schumer, D-N.Y., reflected on the first session of the 117th Congress — which he pointed out "began with Republicans in the majority but quickly switched to Democratic control by the slimmest margins and has become the longest 50-50 Senate in history."

MANCHIN SAYS HE 'CANNOT VOTE' FOR BUILD BACK BETTER: 'I'VE DONE EVERYTHING HUMANLY POSSIBLE'

"We should be proud of our accomplishments," Schumer wrote. "We should also be determined to finish the work that remains undone."

Schumer touted the passage of the American Rescue Plan and the Infrastructure Investment and Jobs Act, which he called "historic pieces of legislation" that are "overwhelmingly supported by the American people." Schumer also highlighted the Senate’s confirmation of "the most diverse class of federal judges in history."

Senate Majority Leader Chuck Schumer of N.Y., speaks to the media after a Democratic policy luncheon, Tuesday, Oct. 19, 2021, on Capitol Hill in Washington. (AP Photo/Jacquelyn Martin)

But in a swipe at the Manchin, Schumer turned attention to the West Virginia moderate, who announced Sunday that, after months of negotiations, he has determined that there is no way he can support Biden's massive social spending bill, known as the Build Back Better Act.

"That frustration was evident in the past week as nearly all of us were disappointed by the decision to delay floor consideration of the Build Back Better Act because Senator Manchin could not come to an agreement with the president," Schumer wrote.

Manchin told "Fox News Sunday" that he spoke with Biden, Schumer and House Speaker Nancy Pelosi, D-Calif., to notify them of his decision.

But Schumer, in his memo to colleagues early Monday, said neither Manchin’s "delay, nor other recent pronouncements, will deter us from continuing to try to find a way forward."

"We simply cannot give up," Schumer wrote, adding that senators "should be aware that the Senate will, in fact, consider the Build Back Better Act, very early in the new year so that every Member of this body has the opportunity to make their position known on the Senate floor, not just on television."

"We are going to vote on a revised version of the House-passed Build Back Better Act—and we will keep voting on it until we get something done," Schumer wrote.

Additionally, Schumer announced to colleagues that when Congress resumes in January, the Senate, "as early as the first week back," will also consider voting rights legislation. Schumer slammed Republicans for having "obstructed" previous attempts to debate the legislation with filibusters.

BUILD BACK BETTER BILL ACCUSED OF MAKING IT ‘VIRTUALLY IMPOSSIBLE’ FOR RELIGIOUS CHILD CARE TO RECEIVE FUNDING

Schumer went on to threaten that Democrats would explore ways to get rid of the filibuster should Republicans use the tool to block debate on the bill, saying rules have been "weaponized to allow a minority of senators to prevent the body from mere consideration of legislation."

"If Senate Republicans continue to abuse the filibuster and prevent the body from considering this bill, the Senate will then consider changes to any rules which prevent us from debating and reaching final conclusion on important legislation," Schumer wrote.

As for the filibuster, Biden in October said he was open to the possibility of altering or eliminating the filibuster in order to pass federal voting rights legislation.

Progressives have repeatedly called on Biden to support abolishing the filibuster to address election reforms. Republicans have used the filibuster to block votes on Democrat-backed legislation multiple times.

The filibuster is a threshold of 60 votes in the Senate that's necessary before a piece of legislation is given an up or down vote.

If Democrats wanted to establish a new filibuster precedent, they could do so with 51 votes – all 50 senators in the Democratic caucus plus Vice President Harris breaking the tie.

Manchin on Sunday said he could not "vote to continue" with the Build Back Better Act, noting that if he cannot explain to his constituents why he would vote for a bill, then he cannot vote for it, despite all of the work he and other Democrats had put in trying to come to a consensus.

"This is a no," he said. "I have tried everything I know to do."

Manchin acknowledged that there were aspects of the bill he was in favor of, but it was just too hefty for him to justify voting for it.

"There’s a lot of good, but that bill is a mammoth piece of legislation," Manchin said, pointing out that it is not even being voted on like a normal bill but being pushed through budget reconciliation.

CLICK HERE TO GET THE FOX NEWS APP

Manchin had previously proposed a $1.7 trillion price tag for the spending package, but he said his Democratic colleagues did not make the necessary compromises. He did note that both he and Biden tried hard to make it work.

"What we need to do is get our financial house in order, but be able to pay for what we do and do what we pay for," he said.

Fox News' Ronn Blitzer contributed to this report.