Budget hawk Rand Paul threatened Tuesday to oppose the Senate spending plan if it increases the U.S. deficit, a move that could kill the deal in a Senate with a slim Republican majority.
"I've told them I'm a 'yes' if they'll not exceed the budget caps," the Kentucky Republican told Politico, referring to the Senate leaders.
"If the leadership is unwilling to compromise with somebody who is concerned about the debt, then they deserve to lose."
Paul also supports proposed tax cuts as long as they do not increase the burden on the middle class.
A Senate budget plan for 2018 could increase the deficit by $1.5 trillion over the next decade. It would also cut spending by $5.1 trillion over the same period, and it claims to balance the budget within 10 years, The Hill reported.
"This budget resolution puts our nation on a path to balance by restraining federal spending, reducing tax burdens and boosting economic growth," Senate Budget Committee Chairman Mike Enzi of Wyoming said when Republican leaders revealed the spending plan last month.
Republicans, with 52 seats in the Senate, have a four-vote majority over the 46 Democrats and two independents who vote with the Democrats.
The House last month passed its own $1.2 trillion budget plan.