Confirmation hearings on presidential nominations are held in fulfillment of the Senate’s constitutional “advice and consent” responsibilities according to the U.S. Constitution.

In the United States, “advice and consent” is a power of the United States Senate to be consulted on and approve treaties signed and appointments made by the President of the United States to public positions, including Cabinet secretaries, federal judges, United States Attorneys, and ambassadors. This power is also held by several state Senates, which are consulted on and approve various appointments made by the state’s chief executive, such as some statewide officials, state departmental heads in the Governor’s cabinet, and state judges (in some states).

All cabinet-level officials, except the White House chief of staff, require Senate confirmation, including: the secretaries of agriculture, commerce, defense, education, energy, health and human services, homeland security, housing and urban development, interior, labor, state, transportation, treasury, and veterans affairs, as well as the attorney general, director of the Office of Management and Budget, administrator of the Environmental Protection Agency, U.S. trade representative, ambassador to the United Nations, chair of the Council of Economic Advisers and administrator of the Small Business Administration.

Hundreds of other senior posts and agency heads (1,212, to be exact) require Senate confirmation, too, after background checks. Essentially, heads of agencies and a lot of deputies need to be confirmed, whereas adviser positions for the president do not. For example: CIA director, yes; national security adviser, no.

Four of President-elect Donald J. Trump’s cabinet choices faced aggressive questions, but avoided any major stumbles.

Representative Tom Price of Georgia, picked to be health secretary, said repealing the Affordable Care Act would not leave millions without health insurance.Mr. Price offered lofty goals for replacing the law but gave few details about the administration’s plans. He did not rule out cuts to Medicare or Medicaid.

Mr. Scott Pruitt, the Oklahoma attorney general and the pick to lead the Environmental Protection Agency, said he disagreed with Mr. Trump’s statement that climate change is a “hoax,” but hedged when asked how much of it is caused by human activity.He defended what he called “common sense” environmental regulation, arguing that farmers, ranchers and business had been hurt by intrusive federal rules.Mr. Pruitt said he would not deny the government’s finding that carbon dioxide and other greenhouse gases are a threat: “That is a law of the land.”