The five entities spending the most on federal lobbying in 2024 were, in order: the National Association of Realtors, U.S. Chamber of Commerce, Pharmaceutical Research & Manufacturers of America, American Hospital Association, and American Medical Association. Key constraints on lobbying include registration and disclosure under the Lobbying Disclosure Act, bans on using federal grant funds for lobbying, and limits on lobbying by tax‑exempt charities.opensecrets+3

Top five big spenders (2024)

• National Association of Realtors (NAR)

  • Spent about 86.4 million dollars on federal lobbying in 2024.opensecrets​

  • Focuses heavily on real‑estate, housing finance, tax, and regulatory issues affecting property transactions and commissions.statista+1

• U.S. Chamber of Commerce

  • Spent about 76.4 million dollars on lobbying in 2024.opensecrets​

  • Represents a wide range of business interests on taxation, regulation, trade, labor, and environmental rules, often advocating broadly pro‑business positions.about.bgov+1

• Pharmaceutical Research & Manufacturers of America (PhRMA)

  • Spent about 31.7 million dollars lobbying in 2024.opensecrets​

  • Represents major drug makers on drug‑pricing, intellectual‑property, Medicare and Medicaid coverage, and FDA regulation.pmc.ncbi.nlm.nih+1

• American Hospital Association (AHA)

  • Spent about 29.0 million dollars on lobbying in 2024.opensecrets​

  • Advocates for hospitals and health systems on Medicare and Medicaid payment, hospital regulations, and large federal health programs.opensecrets​

• American Medical Association (AMA)

  • Spent about 27.8 million dollars on federal lobbying in 2024.opensecrets​

  • Represents physicians on reimbursement, scope‑of‑practice rules, malpractice, and public‑health legislation.opensecrets​

Registration and disclosure rules

• Lobbying Disclosure Act (LDA)

  • Requires lobbyists and their employers to register with Congress if they are paid to lobby covered officials and meet activity and income thresholds.about.bgov+1

  • Registered lobbyists must file periodic public reports listing clients, broad issues, and amounts spent, creating transparency around money spent to influence Congress.about.bgov+1

• Honest Leadership and Open Government Act (HLOGA)

  • Tightened reporting deadlines and expanded electronic, searchable disclosure of lobbying reports.about.bgov​

  • Increased civil and criminal penalties for failing to register or report lobbying activities as required by law.about.bgov​

Limits on use of public and charitable funds

• Ban on using federal grant or contract funds for lobbying

  • Federal law bars recipients of federal grants or contracts from using those federal monies to lobby federal, state, or local officials.law.cornell+1

  • Regulations require grantees to certify they are not using federal funds for lobbying and often to disclose non‑federal lobbying financed from their own resources.hhs+1

• Constraints on 501(c)(3) charities

  • Tax‑exempt public charities may only engage in lobbying to an “insubstantial” degree or within dollar limits under the optional expenditure test.tenenbaumlegal​

  • They are absolutely barred from partisan campaign activity for or against candidates, even though limited issue‑focused lobbying is allowed within IRS rules.tenenbaumlegal​

Other behavioral constraints

• Gift and travel rules

  • Federal lobbyists face strict limits on giving gifts, meals, or travel to Members of Congress and staff, including bans on most privately funded gifts.about.bgov​

  • Congressional ethics rules and HLOGA require pre‑approval and detailed disclosure for many permissible trips involving private funding.about.bgov​

• Revolving‑door and cooling‑off periods

  • Former senior executive and legislative branch officials are restricted from lobbying their former agencies or offices for a defined “cooling‑off” period.pmc.ncbi.nlm.nih​

  • These rules aim to reduce undue influence that could result from immediate post‑government lobbying by recently departed officials.pmc.ncbi.nlm.nih​