WASHINGTON — Chris Klomp’s nomination to become the Health and Human Services Department’s deputy secretary is heading into Senate hearings this week, with Democrats preparing to focus on the administration’s undisclosed agreements with major drug companies. Klomp will appear Tuesday, Sept. 15, before the Senate Finance Committee, which will decide whether to send his nomination to the full Senate. He is scheduled to testify Wednesday before the Senate Health, Education, Labor and Pensions Committee, but that panel will not determine whether his nomination advances. President Donald Trump has pointed to roughly two dozen agreements with drugmakers as evidence of Klomp’s negotiating ability. The deals are intended to reduce the prices of certain medications and encourage companies to expand manufacturing in the United States. The administration also has launched a Trump-branded website through which consumers can buy the medications. But the terms of the agreements have not been made public, drawing criticism from Sen. Ron Wyden of Oregon, the Finance Committee’s top Democrat. Democrats are expected to argue that the administration’s refusal to disclose the details makes it difficult for Congress and the public to determine whether the agreements deliver meaningful savings. “Chris Klomp has been unbelievable, a real star,” Trump said in April while announcing a deal with Regeneron, a New York-based drugmaker. Klomp first took on the drug-price negotiations while serving as Medicare director at the Centers for Medicare and Medicaid Services under Administrator Mehmet Oz. He has served as acting overseer of HHS operations since February, after a leadership shake-up that removed former Deputy Secretary Jim O’Neill and elevated Klomp, who had been HHS Secretary Robert F. Kennedy Jr.’s chief counselor. In that role, Klomp has also been involved in policy and personnel decisions, including the selection of HHS nominees such as Centers for Disease Control and Prevention Director Erica Schwartz. Trump nominated him for the deputy secretary position in June. The hearings are also expected to examine the nation’s measles outbreak, which has grown to nearly 3,300 reported cases, the highest level in 35 years. Pennsylvania has recorded three recent measles-related deaths, including two that prompted a public dispute between Kennedy and Democratic Gov. Josh Shapiro. Democrats are expected to contend that Klomp, as the department’s prospective second-in-command, would bear substantial responsibility for HHS’s operational response to the outbreak. A Democratic memorandum circulated to Finance Committee members also raises questions about whether Klomp owed self-employment taxes in 2022, 2023 and 2024 because of his partnership in Endurance Companies, an asset-management and investment business. Klomp has told Democratic aides that his limited involvement did not make him liable for those taxes. A person involved in the nomination process said Klomp’s accounting advisers and the Joint Committee on Taxation, which reviewed his returns, concluded that he complied with tax law and did not need to file amended returns. HHS had not responded to questions about the upcoming hearings.