The Republican-led Senate is expected to confirm a chief architect of Project 2025 as director of the Office of Management and Budget on Thursday, despite round-the-clock speeches by Democrats who lack the votes to stop it.

Mr. Vought, an architect of Project 2025 who served in the first Trump administration, will be at the center of President Trump’s plans to upend the federal bureaucracy.

Democrats see Vought as the embodiment of a Trump agenda that they want to build their opposition message around — from his long-standing ties to Project 2025 to his support for slashing spending programs that benefit the middle class to his election denial.