Story highlights GOP leaders can only afford to lose two Republicans and pass the tax plan

This Oklahoma Republican said he is deeply concerned about the impact of the bill

(CNN) Sen. James Lankford said Monday the Senate tax reform proposal needs to include a back-up plan to pay for it in case the economic growth projections conservatives are banking on don't materialize.

The Oklahoma Republican says he is deeply concerned about the impact of the tax bill on the debt and deficit especially if the 0.4% growth projections anticipated by the tax changes don't hold up. He is working with GOP leadership and members of the Senate Finance Committee to craft a "what if" plan if they don't.

"What if the growth estimates don't hit point 0.4%? What happens? What should happen in the tax code to make adjustments? Every economist is guessing," he said at a Capitol news conference. "We should build in the what if. What if this doesn't work? What changes might be needed in the tax code in the days ahead to be able to adjust in what scenario? So, if the revenues aren't coming in, should the rates change? All of those are in conversation."

Lankford said he and his staff worked with tax negotiators over the Thanksgiving break to address his concerns and those talks continue.

"The conversations have been extremely productive," he said. "No one is pushing back. No one is saying, 'no we don't want to do this.' It's just, how do we get it done? How do we get it through the parliamentary process?"

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