Sen. Bernie Sanders challenged Republicans not to use deficit increases to justify future cuts to entitlement benefits Thursday in a heated exchange during a debate on their tax reform bill.

Senate Republicans are nearing a final vote on their bill to overhaul the tax code – with the promise that it will help people across the country by reducing rates and boosting economic growth. Democrats and other critics warn the bill mostly just benefits the rich and large corporations. Sanders, while speaking on the floor prior to an expected vote, argued that deficit increases from the bill would be used to justify cuts to Social Security, Medicare, and Medicaid.

“It is my absolute belief that as soon as this tax proposal is completed and drives the deficit up by $1.4 trillion, I have zero doubt that my Republican colleagues are going to come back to the floor of the Senate and suddenly say, oh my goodness, the deficit has gone up, we are going to have to cut Social Security, Medicare, and Medicaid,” Sanders declared.

Sanders has proposed an amendment to the tax bill that would establish a rule requiring a two-thirds vote in order to cut Social Security, Medicare, and Medicaid. He promised he would withdraw the amendment if Republicans could guarantee to the American people that they won’t make those cuts – singling out Senate Majority Leader Mitch McConnell, Pennsylvania Sen. Pat Toomey, and Florida Sen. Marco Rubio. He yielded his time to talk so they could answer.

“It would surprise my friend to know that in Florida we have a lot of people on Medicare and Social Security, one of them is my mother,” Rubio answered. “If I were to cut her Medicare and Social security, I probably would never be able to go home and see her again. So the answer to your question is no. As I’ve been clear time and time again, I believe for future generations like myself, there need to be adjustments made.”

Rubio added that entitlement programs need to be reformed so that they will be there for future generations. But he promised that would not involve cuts to benefits. Toomey responded by noting if they did plan to make those cuts they would have done it with the tax bill which only requires a majority vote because of the reconciliation process – to which Sanders took issue with, noting he asked whether they would come back and try to make the cuts later.

“Are you guaranteeing the American people that you will not be cutting Social Security, Medicare, and Medicaid?” Sanders responded. “Will you guarantee the people of this country that after this bill passes that you will not come back, raise the retirement age, voucherize Medicare, raise the retirement age for Medicare, cut cost of living increases?”

The nonpartisan Congressional Budget Office found Nov. 26 that the legislation could add $1.4 trillion to the deficit over the next decade. Republicans have expressed hope that the increased economic growth could bridge at least some of the gap, and have entertained the idea of federal spending cuts later on. The Joint Committee on Taxation found in a later analysis hours before the expected vote Thursday that the bill would add $1 trillion to the national deficit over the next decade, even with projected economic gains.

“I will not support any cuts to people who are on the program and need those benefits,” Toomey answered. “But I want this program to survive. We need this program for the next generation.”

Sanders prompting interrupted the senator to reclaim his time, arguing his answer clearly indicates he would cut benefits for future recipients, since he said he wouldn’t support cuts to people who are on the program. Sanders added that people in their 50s could soon see cuts to benefits since they haven’t yet reached retirement age and therefore aren’t recipients.

“He just let the cat out of the box, or whatever the phrase is,” Sanders shouted. “He just told you he’s going to cut Social Security. That’s it my friends. He will not cut it, what he just said is he will not cut it for people who are on Social Security right now. I hear that.”

The House has already passed its version of the legislation – which means a successful vote by the Senate will allow them to form a conference committee together. The process allows the two chambers to resolve differences between their versions of the legislation. Once they pass identical bills, they can go onto President Donald Trump to be signed into law.

The vote was delayed shorty after the exchange until Friday with lingering disagreements still persisting among members of the Republican Party.

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