Construction on the new White House ballroom is seen from the Washington Monument on May 5 in Washington. (AP Photo/Julia Demaree Nikhinson)

WASHINGTON (AP) — Senate Majority Leader John Thune is defending a Republican proposal to give the Secret Service up to $1 billion for security upgrades to Donald Trump’s White House ballroom project, saying the total is “what it costs to protect the President of the United States in a very dangerous time and a dangerous world.”

Thune and Senate Republicans returning to Washington on Monday were facing questions about the plan, which GOP senators added to a spending bill after a man was charged with trying to assassinate Trump at the White House Correspondents’ Association dinner last month. Trump has said that his proposed new ballroom would cost around $400 million and be paid for with private money, but the White House had not previously proposed a number for security costs.

“Keeping the leader of the free world safe is an expensive proposition,” Thune said. “The Secret Service has a job to defend and protect the president, and we need to make sure they have the tools to do it.”

Democrats say they will try and defeat the plan, which Republicans added to a spending bill that would restore funding for immigration enforcement agencies that the Democrats have blocked since February.

Senate Democratic leader Chuck Schumer noted that Trump said a few months ago not one penny of taxpayer money would be used for the ballroom.

“Well, give me a break. He’s put a billion dollars in the budget for it. This staggering waste of taxpayer dollars has nothing, nothing to do with security and everything to do with Trump’s ego,” Schumer said.

Republicans are using a partisan budget maneuver to push the spending legislation through Congress without any Democratic votes. But Schumer said Democrats will fight it in other ways, including by pushing the Senate parliamentarian to strike the ballroom security money from the budget bill and by offering amendments that force Republicans to vote on it.

It’s unclear if the security money will even have enough backing among Republicans to advance. While most GOP lawmakers have remained quiet on the proposal as they spent their recess out of Washington, some have publicly questioned whether they would support it.