That agreement, which ended an hours-long partial government shutdown, boosts government spending by almost $300 billion. Mulvaney said that in his previous job as a fiscally-conservative congressman representing South Carolina, he would “probably not” have voted for the bill.

The additional spending could increase the deficit to about $1.2 trillion in 2019, and there’s a risk that interest rates “will spike” as a result, Mulvaney said.

U.S. Treasury yields have been rising in recent weeks on worries that inflation is heating up as the spending package juices an economy already souped up by tax cuts and at or near full employment.