WASHINGTON, DC - JANUARY 10:  Mark R. Warner (D-VA), Vice Chair of the Senate Select Committee on Intelligence, speaks during the Senate (Select) Intelligence Committee in the Dirksen Senate Office Building on Capitol Hill January 10, 2017 in Washington, DC.  The committee was holding a hearing about cyber threats to the United States and fielded questions about effects of Russian government hacking on the 2016 presidential election.  (Photo by Joe Raedle/Getty Images)
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WASHINGTON, DC - JANUARY 10: Mark R. Warner (D-VA), Vice Chair of the Senate Select Committee on Intelligence, speaks during the Senate (Select) Intelligence Committee in the Dirksen Senate Office Building on Capitol Hill January 10, 2017 in Washington, DC. The committee was holding a hearing about cyber threats to the United States and fielded questions about effects of Russian government hacking on the 2016 presidential election. (Photo by Joe Raedle/Getty Images)
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(CNN) —  

Sen. Mark Warner said his chamber’s passage of the Republican tax reform bill Saturday morning was his “single worst day as a US senator,” adding that the GOP’s last-minute bill changes were “swamp 101.”

“(A)s somebody who wanted to be a part of tax reform, and realizes we need to have a more competitive corporate rate, that realizes we need to bring back some of those American profits, there are three things about this process that just plain stunk,” the Virginia Democrat said Sunday on CNN’s “State of the Union.”

One of the “swamp 101” provisions was a special tax break for Hillsdale College, he said.

“Friday night (when) the bill was being hand-drafted, lots of provisions were being included for special interests. One got exposed already, exempting a particular religious college in Michigan backed by the DeVos family for special tax breaks,” Warner said.

Warner was referring to language that was ultimately struck from the GOP tax bill that would have given a tax exemption exclusively to the small college in Michigan, which has ties to the Trump administration, including Education Secretary Betsy Devos, whose brother, Blackwater security firm founder Erik Prince, was a graduate.

“I bet you we will see literally dozens more of these special provisions put in to help special interests,” Warner continued.

Warner added that he believes the bill “will add over $2 trillion to the debt” and incentivize American companies to move business abroad.

Sen. Tim Scott, R-South Carolina, pushed back on the nonpartisan Joint Committee on Taxation’s estimate that the bill would add $1 trillion to the deficit, telling “State of the Union” anchor Jake Tapper that the committee “consistently” underestimates economic activity.

“(O)ne thing you can conclude of the last eight years is that our debt went from $10 trillion to $20 trillion” Scott said. “Our economy stalled. If we continue to spend more than we make … and our debt continues to explode, we do burden the next generation with more and more debt. One of the fastest ways to fix that is economic growth. … Our tax code must be competitive with the rest of the world.”

Scott also justified the GOP’s last-minute add-ons to the Senate tax bill Friday evening, saying that they’ve been discussed in hearings and meetings for years.

“That last hour was not the accumulation of new information, it was the culmination of three years. … We certainly knew what was in the bill long far before the last pages were printed,” he said.

The House and Senate will now head to a conference committee to reconcile the differences between their respective versions of tax overhaul bill, but Warner said he thinks “there still remains some chance” tax reform will not pass.