Some members are concerned the GOP tax overhaul would lead to mandatory multi-billion dollar cuts to programs such as Medicare.

There’s not enough mandatory spending up for grabs under current law to execute the full automatic, across-the-board spending cuts to entitlement programs that would be triggered if Republicans push through deficit-increasing tax cuts by year’s end.

That was the message from the Congressional Budget Office Tuesday in a report to House Minority Whip Steny H. Hoyer, D-Md. CBO calculated if the tax package were to add up to $1.5 trillion to the deficit over 10 years as currently expected, automatic cuts required under the 2010 pay-as-you-go law would amount to $136 billion in fiscal 2018.

The spending cuts, known as a sequester, would be triggered if the tax cuts added to the deficit and lawmakers didn’t vote to “wipe the scorecard clean,” as lawmakers have characterized their action to waive the so-called pay-go law in previous years.

Otherwise, the law requires the Office of Management and Budget to make across-the-board cuts to nonexempt mandatory spending programs if action during a congressional session contributes to the deficit over the five- or 10-year budget window, according to OMB’s annual budget scorecard. The issue was raised by Senate Democrats in October, who warned Democratic support for a pay-go waiver wasn’t guaranteed.