U.S. Republican Party Senators adopt a ban on earmarking, or setting aside money in bills for specific purposes specified by legislators.
- Two new Democratic senators—Doug Jones of Alabama and Tina Smith of Minnesota—are sworn in, bringing the Republican majority down to 51–49.
- Voters in Alabama go to the polls to fill the United States Senate seat vacated by current United States Attorney General Jeff Sessions. The race is between Roy Moore (R) and Doug Jones (D).
- United States senators Ben Cardin (D-MD) and Marco Rubio (R-FL) file a bill restricting arms sales to the Philippine National Police over its drug war.
- The Republican-controlled United States House of Representatives votes in favor of the repeal of the 2010 Patient Protection and Affordable Care Act and passage of the House's 2017 American Health Care Act, by a narrow, 217-213 vote. Twenty Republicans and all Democrats opposed the bill, which now heads to the United States Senate for its legislative action.
- The U.S. Senate confirms Donald Trump's appointment of his former opponents in the presidential primaries, neurosurgeon Ben Carson and Governor of Texas Rick Perry, as Secretaries of Housing and Urban Development and Energy respectively, with the support of all Republicans and some Democrats.