Senate Republicans rebuked President Biden Wednesday by tanking a key test vote on his request to provide billions in support to Ukraine, Israel and Taiwan — hours after he accused them of “playing chicken with our national security.”

The upper chamber voted 51-49 against opening debate on the president’s $106 billion national security supplemental funding ask — which the White House insists must be passed before Congress goes home for the holidays — as the GOP demands substantive changes in immigration policy.

The bill needed 60 “aye” votes to clear the initial hurdle. All 49 Senate Republicans voted “nay,” along with Sen. Bernie Sanders (I-Vt.) and Senate Majority Leader Chuck Schumer (D-NY), the latter of whom did so for procedural reasons.

“Extreme Republicans are playing chicken with our national security, holding Ukraine’s funding hostage to their extreme partisan border policies,” Biden said hours earlier from the White House Roosevelt Room — in which he acknowledged that the US is dealing with a “broken border system.”

“I am willing to make significant compromises on the border,” he claimed. ” … It is broken. And thus far, I’ve gotten no response.”

The president said he had “asked for billions of dollars for more border agents, more immigration judges, more asylum officers,” but mentioned nothing about policy changes during his address.

“Republicans have to decide if they want a political issue or if they want a solution at the border. Do they really want a solution?” he asked. “We need a real solution.”

The White House and congressional Republicans have gone back and forth all week over the supplemental request.

Biden’s Office of Management and Budget sent a letter to House Speaker Mike Johnson (R-La.) on Monday warning that Ukraine military aid, most of which has gone to the US defense industrial base, will run out by year’s end.

Johnson responded Tuesday that Capitol Hill Republicans would not support additional aid without “transformative change” to America’s border policies

“For the better part of two years, the brave people of Ukraine have denied Russia a victory on the battlefield. They’ve defeated [Russian President] Vladimir Putin’s ambition to dominate Ukraine,” Biden said Wednesday.

“And the people of the United States can and should take pride — they should take pride that we’ve enabled Ukraine’s success thanks to the steady supply of weapons and ammunition we’ve provided them together with our partners and our allies.”

Biden then accused Republicans of being “willing to give Putin the greatest gift he could hope for,” saying “Democrats have put forward a bipartisan compromise on the table” in the Senate by allowing for immigration-related amendments to the supplemental request

Sen. James Lankford (R-Okla.), who has led the Republican negotiators in the upper chamber, disagreed.

“Obviously, the White House originated this. They started by saying ‘We’re going to do Ukraine, Israel, Indo-Pacific and border security at the same time,’” Lankford told The Post in an interview before the vote.

“We have just said, ‘Absolutely. And we are not going to just give you more money to process people faster into the country,’” he said. “We will allow additional dollars when we have a change in policy and a change in direction so that we’re actually controlling the border, not just managing releases.”

Lankford added that reforms to asylum policy were particularly needed, with thousands of migrants rushing across the border every day to ask for humanitarian parole before being released into the country.

“We’re pushing and saying, ‘If it’s not more obvious now that we’ve had 2.5 million people that have crossed the border illegally in the last year, and we’re now up to 10,000 people a day that are crossing the border — if it’s not obvious now this is a need, when would it be obvious?'”

After the vote, Lankford told reporters that negotiations between him and Sen. Chris Murphy (D-Conn.) would move forward — despite ongoing frustration and worries about a stalemate extending later into the month.

“This is not going to move without significant policy,” he said. “Thankfully, the president stepped out today and said he understands that as well.”

There remains “roughly $4.8 billion” in previously authorized funds the US can send Ukraine in future military packages as the war approaches its two-year anniversary in February, Pentagon spokesman Air Force Brig. Gen. Pat Ryder said Tuesday.

“We may reach a point where we can’t sustain the current level of security assistance support,” he said. “We need Congress to support now so that we can provide Ukraine with the capabilities that they urgently need to defend themselves.”

If that point comes, Defense Secretary Lloyd Austin told Congress last month, a halt in support raises the risk that Russia will defeat Ukraine and subsequently attack NATO countries, bringing the US into combat. 

“If the US does not continue to support Ukraine,” Austin told the Senate Appropriations Committee, “they will not succeed.”