(AP) -- Under the U.S. Constitution, the Senate has sole authority to confirm a president's nominee to serve in the Cabinet. And while President-elect Donald Trump can't officially nominate anyone until he becomes president Jan. 20, the Senate is getting an early start this week on his choices for several top jobs in his administration.
The action began Tuesday with Trump's pick for attorney general, Jeff Sessions, a longtime senator from Alabama, and retired Marine Gen. John Kelly, named by Trump to head the Department of Homeland Security.
By holding hearings before Inauguration Day, the Senate can move quickly once Trump takes the oath of office and formally submits his Cabinet nominees for approval.
Republicans have a narrow majority in the Senate, meaning the hearings are unlikely to make or break nominations. Most, if not all, will go through.
But the hearings offer senators an opportunity to explore the backgrounds of Trump's team and plans for the agencies they will soon lead. For Democrats, the hearings offer a high-profile stage to challenge Trump's proposals.
The lead-off confirmation hearing was Alabama Sen. Jeff Sessions, one of the most conservative members of the Senate and a pick that has generated some of the strongest Democratic opposition.
Trump's pick for Homeland Security secretary isn't controversial, unlike the issues he'll potentially face in office.
Retired Marine Gen. John Kelly is well-regarded by Democrats and Republicans alike and his confirmation is almost assured. He joined the Marines in 1970, served three tours in Iraq and is the former head of U.S.
Most, if not all, of Trump's picks are expected to win confirmation. While Republicans only hold a 52-48 advantage in the Senate, Democrats changed the Senate's filibuster rules in 2013. That means Trump's choice can win confirmation on a simple majority vote along party lines.
The independent Office of Government Ethics, responsible for ensuring nominees avoid any conflicts of interest, told the Senate late last week that in some cases it hadn't received even draft financial disclosure reports for nominees slated to appear before the Senate this week.
The confirmation hearings for education secretary Betsy DeVos, a Michigan billionaire, and Andrew Puzder, a fast-food executive and choice for labor secretary, were both postponed Tuesday.