A US Senate official on Saturday removed security funding that could be used for Donald Trump’s planned $400m White House ballroom from a massive spending package, Democratic lawmakers said, imperilling Republican efforts to devote taxpayer money to the contentious project.

The decision by the Senate’s parliamentarian, Elizabeth MacDonough, deals a blow to Trump and his administration, which has sought the money for security purposes related to the ballroom.

Trump has said construction of the ballroom will be funded by private donors. But Senate Republicans are seeking $1bn in taxpayer funding to the Secret Service for security upgrades, including the ballroom, even though the bulk of the legislation is devoted to immigration enforcement.

Trump’s congressional allies are invoking complex budget rules to secure passage without any Democratic support. Democrats have opposed funding for Trump’s signature immigration crackdown absent reforms they have sought since federal immigration agents killed US citizens in separate incidents in Minnesota in January.

Ryan Wrasse, a spokesperson for Senate majority leader John Thune, wrote in a post on X that “none of this is abnormal” during the complicated budget process that Republicans are using to try to pass the immigration enforcement and White House security money on a partisan basis.

“Redraft. Refine. Resubmit,” Wrasse said in the post.

Republicans hold a 53-47 majority in the Senate, leaving them short of the 60 votes needed to pass most legislation under the chamber’s rules. Democrats have criticized the ballroom as an expensive and frivolous diversion by Trump at a time when Americans face rising costs such as higher fuel prices.

Republicans have said the ballroom-related spending they are pursuing is needed to ensure presidential safety, citing an April incident in which a gunman tried to storm a black-tie media gala in Washington that Trump attended.

The Republican senator Bill Cassidy lost his primary on Saturday, as voters in Louisiana opted instead to advance two challengers to a runoff election after an extraordinary intervention by Donald Trump to oust the incumbent.

With two days to go before the next big test of Donald Trump’s iron grip over his party, the president went head-to-head on Sunday with his nemesis, Thomas Massie the Kentucky congressman who is in a fight for his political life in Tuesday’s Republican primary.