Senate Majority Whip Dick Durbin (D-Ill.) told reporters Thursday that he was “stunned” to discover that Sen. Joe Manchin (D-W.Va.) is opposed to a one-year extension of the expanded child tax credit, a core component of President Biden’s agenda.

Durbin said he’s “frustrated and disappointed” while acknowledging that Biden’s sweeping social spending and climate bill doesn’t appear to be headed to the president’s desk anytime soon.

“We had more than ample opportunity to reach ... a Democratic agreement — I never assumed any bipartisan support. We missed an opportunity but I’m not giving up,” he said.

Durbin also said that Democrats were counting on a one-year extension of the tax credit and thought there was an agreement between Manchin and White House negotiators.

But Manchin recently told White House negotiators that he wants the Build Back Better bill to include a 10-year extension of the expanded child tax credit so that its true cost is reflected in the official Congressional Budget Office score of the bill.

At the same time, he wants to keep the overall cost of the bill at $1.75 trillion, which means there would be little room for other Democratic priorities. A 10-year extension of the expanded child tax credit would cost about $1.5 trillion alone.

That would leave only $250 billion to $350 billion for other priorities such as long-term home health care, expanded child care subsidies, universal prekindergarten and raising the cap on state and local tax deductions.

“I was stunned by that,” Durbin said on Thursday when asked about his reaction to the late-breaking news that Manchin didn’t want to include a one-year extension of the expanded child tax credit. “That is such a critical element — the largest tax cut for working Americans in the history of the United States. We were so proud of what we accomplished there and for this to come up as an issue toward the end was stunning.”

He added that “the level of emotion in our caucus about that child tax credit is very high.”

The $1.9 trillion American Rescue Plan that Democrats passed in March expanded the child tax credit from $2,000 per child to $3,000 per child and $3,600 per child under the age of 6. That expansion is due to expire at the end of the month.

Durbin said he didn’t know the best way to save the bill at this point or whether it needs to be broken up into smaller pieces to make it easier to negotiate and pass.

He said a key difficulty is that Manchin’s stance in the talks appears to be hard to pin down.

“Apparently, Manchin’s approach to this has changed a lot. I don’t know where he is today or where he’ll be tomorrow,” he added.

Durbin rejected the notion, however, that Biden hasn’t done enough to cajole Manchin into supporting his signature domestic social spending initiative.

“I think Manchin has been camped out in the Lincoln Bedroom and has his own parking space at the White House, he’s been there so often. I couldn’t ask for Joe Biden to do more in his effort to find common ground with Joe Manchin,” he added.

Sen. Michael Bennet (D-Colo.), a leading proponent of the expanded child tax credit, said on Wednesday that Democratic senators were told earlier this year that Manchin had agreed with the White House to a one-year extension of the provision.

“I believe that there was an agreement to extend child tax credit for a year and to make its full refundability permanent between people who were negotiating this with the White House,” he told reporters.

Republicans celebrated the bill’s collapse on Thursday, predicting it’s not likely to become law in its current form.

“I think Build Back Better is dead forever, and let me tell you why: because Joe Manchin has said he's not going to vote for a bill that will add to the deficit,” Sen. Lindsey Graham (R-S.C.) said during an appearance on Fox News’s “Hannity.”

Senate Minority Leader Mitch McConnell (R-Ky.) also spiked the football on Thursday morning.

“We got indications the far left’s slapdash sprint may be hitting the pause button. That would be great news for the American people. The best Christmas gift Washington could give working families would be putting this bad bill on ice,” he said on the Senate floor.