A White House official lashed out at GOP senators Thursday, saying that Sen. Lindsey Graham of South Carolina was “an obstacle” on immigration reform who had attacked “heroes,” and questioning whether Republicans sponsoring a compromise immigration bill understood their own legislation.

The official stressed White House support for an immigration bill sponsored by Sen. Chuck Grassley, R-Iowa, that closely follows President Trump’s immigration priorities — legal status for young illegal immigrants, a border wall and new limits on legal immigration — and opposition to legislation backed by Senate Minority Leader Chuck Schumer, D-N.Y., and eight Republicans, led by Sens. Susan Collins, R-Maine, and Mike Rounds, R-S.D.

“The bill is so spectacularly poorly written ... that I can announce we are officially asking the sponsors of the bill to withdraw their sponsorship, allowing for the possibility that they were simply grievously misinformed about the bill’s outrageous contents,” the official said on a background call with reporters.

The White House and conservative Republicans have said the legislation up for a Senate vote later in the day goes far beyond the initial idea of finding a way to help 1.8 million young illegal immigrants eligible for the Deferred Action for Childhood Arrivals program, and instead would deprioritize immigration enforcement for most of the millions of illegal immigrants in the country.

The official denounced Graham by name for saying he had “stopped paying attention” to the Department of Homeland Security after a strongly worded press release against the bipartisan bill. Graham said that DHS statement was "over the top” and “poisonous.”

“I want to make a quick note about Sen. Graham's attacks on the Department of Homeland Security. The men and women who work that the Department of Homeland Security are heroes, they keep us safe,” the official said.

“The operators at DHS have painstakingly, for months, outlined for Congress the reforms they need to protect and save American lives and national security. Senator Graham has been an obstacle to those reforms, has been an obstacle to including the measures we need to keep America safe, has been an obstacle to what rank and file law enforcement officers need to do their jobs, and in that sense he’s been an obstacle to immigration reform, he’s been an obstacle to getting relief for Dreamers," the official said. "If you look at the history of failed immigration reform bills, at some point you have to ask yourself the question: whether Lindsey Graham’s involvement in drafting the bills means that instead of being the solution to the problem, Lindsey Graham’s involvement on those bills is the problem.”

The official said the compromise measure's proposed limit on chain migration for young illegal immigrants, who would gain citizenship but not be allowed to sponsor their parents if they brought them to the U.S. illegally, was unworkable and possibly unconstitutional.

Another Trump administration official on the call attacked the bipartisan bill by saying a provision halting enforcement action against illegal immigrants who arrive before June would cause a rush to the border. That language was changed at the last minute Thursday, just before a vote on that and three other proposals was expected.