Democrats are in shock after Sen. Joe Manchin III, D-W.Va., announced on “Fox News Sunday” that he is a “no” vote on President Biden’s massive multitrillion-dollar reconciliation plan — killing the bill.

They should not have been surprised. Manchin laid out his demands in a document that was signed by Senate Majority Leader Charles E. Schumer (N.Y.) and later released to his colleagues and the public. In a 50-50 Senate he wasn’t just one of 50 Democrats whose views needed to be taken into account in crafting a deal. He had a veto. If they didn’t get his vote, they got nothing. And Manchin said over and over again that he was comfortable with nothing. They didn’t believe him.

Democrats tried to twist Manchin’s arm but had no leverage. A December poll showed West Virginia voters shared Manchin’s worries about Biden’s plan: 59 percent opposed the bill; 73 percent said inflation had hurt their family’s finances; and 64 percent said Build Back Better would make inflation worse.

Manchin agreed to support $1.5 trillion — which he later raised to $1.75 trillion. That’s a lot of money. But instead of eliminating programs to scale down their bill, Democrats tried to jam him with budget gimmicks — using expiration dates to fund all their programs for a shorter period of time, making the cost of the bill seem smaller than it really was.

Manchin is not stupid. He saw what they are doing. He knew the nonpartisan Penn Wharton Budget Model estimated in October that the bill could cost $3.9 trillion over the next decade without the “sunsets” — and that the Congressional Budget Office scored the cost of the bill at $3.47 trillion if the programs were funded over 10 years. And as he made clear, he was not going to support a bill that cost that much.

On Sunday, Manchin explained the reason he decided to oppose the bill is that “it hasn’t shrunk.” Instead of cutting the number of programs, he said, Democrats kept “the same amount of things that they are trying to accomplish” but just changed “the amount of time . . . that we can depend on them.” If you’re going to do something, Manchin said, “pick what your priorities are — like most people do in their families or their businesses — and you fund them for 10 years.”

So what was Manchin willing to support? He said this past week that he supported expanding the child tax credit, as long as it was funded for 10 years. The CBO scored the 10-year cost of the child credit at $1.597 trillion. Biden and Schumer could have agreed to that, and then found a way to spend the remaining $150 billion. If they were willing to scale back their ambitions, they could have easily passed a reconciliation bill with his support.

They had already passed a $1.2 trillion bipartisan infrastructure bill that contained a lot of progressive priorities, including funding to replace lead pipes; expand broadband to underserved communities; electrify the nation’s fleet of public buses; create plug-in electric vehicle infrastructure; reduce emissions at airports, ports and waterways; expand clean energy transmission; and make our infrastructure more resilient against the effects of climate change. If they had combined that with a Build Back Better bill Manchin could support, Biden could have claimed credit for almost $3 trillion in new spending, on top of the $1.9 trillion in social spending disguised as “coronavirus relief” passed with only Democratic votes earlier this year. That would have been a huge progressive win.

But apparently that wasn’t enough if it did not contain everything the party’s progressive wing wanted. Instead of declaring victory, Democrats refused to accept the reality of their situation and compromise with Manchin. They assumed eventually he’d fall in line. They were wrong.

Now Democrats are lashing out at Manchin, blaming him for delivering the president a major defeat. But the truth is, they are the authors of their own defeat. Biden and Schumer miscalculated badly and lost — they have no one to blame but themselves.