Treasury Secretary Steven Mnuchin has urged lawmakers to give President Trump a line-item veto, saying on “Fox News Sunday” that it might prevent Democrats from stacking more nondefense discretionary spending into the next must-past budget bill.

But Mnuchin’s short exchange with Fox News anchor Chris Wallace also underlined the problem with the idea — a 20-year-old Supreme Court ruling that struck down the line-item veto, finding “no provision in the Constitution that authorizes the president to enact, to amend or to repeal statutes,” after President Bill Clinton used it 82 times.

“I think they should give the president a line-item veto,” said Mnuchin, echoing Trump’s comments after he signed last week’s omnibus budget bill.

“That’s been ruled unconstitutional by the Supreme Court,” Wallace said.

“Well, again, Congress could pass a rule, okay, that allows them to do it,” Mnuchin said.

“It would be a constitutional amendment,” Wallace said.

“Chris, we don’t need to get into a debate,” the treasury secretary said. “There’s different ways of doing this.”

Since 1998, Congress and presidents of both parties have made halting attempts at restoring the line-item veto. In 2006, George W. Bush’s administration got behind the Legislative Line-Item Veto Act, which passed the Republican-controlled House but died in the Republican-controlled Senate. In 2011, a new Republican-led House advanced the Expedited Legislative Line-Item Veto and Rescissions Act, which also died in the Senate. Both bills were backed by future House speaker Paul D. Ryan (R-Wis.). Both had bipartisan support.

Hours after he threatened to veto, President Trump signs omnibus spending bill into law, averting a government shutdown. (The Washington Post)

There has been no similar groundswell for a line-item veto in this Congress, in part because the issue has become more partisan. Trump’s new interest in veto power comes as he accuses Democrats of using the omnibus negotiations to fund some of their priorities. (“The Democrats demanded a massive increase in nonmilitary spending,” Mnuchin said.) The rapidly passed bill outraged some of the president’s supporters, who had perked up at rumors that he might veto it all and make Congress start over.

“This could have been written by President Obama and liberal Democrats,” Sen. Rand Paul (R-Ky.) said of the budget last week.

Mnuchin did not discuss an idea that has circulated on the right — simply not spending money appropriated by Congress. The “impoundment” process also has been struck down by the Supreme Court; the 1974 Congressional Budget and Impoundment Control Act, passed by a Democratic Congress, was for a long time the last word on whether the executive branch could simply decline to spend money.

But the Trump administration already has played around the edges of impoundment. Before being let go this month, Secretary of State Rex Tillerson drew fire from Democrats for not spending $80 million appropriated to fight terrorist propaganda and Russian election interference. After being named acting director of the Consumer Finance Protection Bureau, OMB chief Mick Mulvaney requested no money for the watchdog agency.