Rep. Chip Roy (R-TX) is outlining his latest demands in the fight over appropriations and government spending, issuing an ultimatum to the Biden White House in exchange for his support on the must-pass legislation: the ouster of Homeland Security Secretary Alejandro Mayorkas.

In a Dear Colleague letter sent out to lawmakers on Tuesday, Roy listed a number of demands the Texas Republican said must be met in order for him to support legislation funding the Department of Homeland Security or to vote for a continuing resolution ahead of the looming Sept. 30 deadline. Those demands include measures to tighten security at the southern border, which Roy argues is a “national crisis.”

“Enacting a CR would unacceptably mean continuing the funding level and policies of the disastrous FY 2023 omnibus, which Speaker [Kevin] McCarthy correctly argued perpetuates the border crisis,” Roy wrote. “Passing a full-year DHS appropriations bill without forcing the significant change necessary to secure the southern border is equally objectionable, even with some policy riders.”

In his Tuesday letter, Roy laid out four conditions that must be met in order for him to support any spending legislation, pressing the Biden administration to implement stronger border security measures. One of the conditions urges President Joe Biden to sign H.R. 2, a GOP-led measure passed by the House earlier this year that has been lauded by Republicans as the “strongest border security bill” passed by lawmakers in decades.

The letter also pushes the president to implement policies that give law enforcement officials the “tools necessary” to combat cartels attempting to cross the border, as well as a $10 billion reimbursement to the state of Texas for expenses used to secure the border.

Roy also demands the ouster of Mayorkas from his position as the head of DHS, urging the president to ensure he “is removed from office, resigns, or is fired.”

“Simply put, no member of Congress should agree to fund a federal agency at war with his state and people. We have a moral obligation to protect our states, our nation, and, importantly, the migrant children getting abused from the disaster transpiring at our southern border,” Roy wrote. “No border security, no funding.”

The letter comes after House lawmakers left Washington, D.C., for its six-week recess despite a lengthy to-do list and lingering negotiations over spending legislation. House leaders said they would continue working over the break, although it remains unclear whether lawmakers will meet in person to do so.

The House managed to pass its military construction appropriations bill before it adjourned, advancing only one of 12 of its must-pass spending bills before leaving town and returning on Sept. 12. That leaves Congress with just 18 days upon its return to pass its budget and avert a government shutdown.

It’s unclear whether the House would approve a continuing resolution, an agreement that allows the government to operate at the same spending levels until a new budget is passed, as some hard-line conservatives including Roy said they would oppose such a measure.

“I will not vote for a CR,” Roy said before the House left for recess last month. “I will not help advance a CR in any way, shape, or form.”