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 on 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.
Here's a look at this week's confirmation hearings:
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.
Sessions promised that as America's top law enforcement officer, he would crack down on illegal immigration, gun violence and "radical Islamic terrorism." He said he opposes barring Muslims from entering the United States, a Trump campaign proposal from which the Republican later backed away.
Sessions also promised to recuse himself from any investigation into former Democratic presidential candidate Hillary Clinton, citing comments he'd made during the campaign. The FBI concluded last year that Clinton should not face criminal charges for using a private email system while serving as secretary of state.
Democrats have questioned Sessions' commitment to civil rights and oppose his hard line position on immigration. One Democratic senator, Cory Booker of New Jersey, plans to testify against Sessions — a rare instance of a senator testifying against a colleague seeking a Cabinet post.
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. Southern Command, which works closely with Homeland Security on issues that include drug smuggling and illegal immigration. His son, Marine 1st Lt. Robert Kelly, was killed in Afghanistan.
As Homeland Security secretary, Kelly would have a key role in advancing Trump's agenda on immigration and border security, including the president-elect's promise to build a wall on the Mexican border and to deport millions of immigrants living in the U.S. illegally.
Kelly told lawmakers that preventing the "illegal movement of people and things" would be his top priority if confirmed.
Republicans and Democrats came away from a confirmation hearing Tuesday singing Kelly's praises.
Democratic Sen. Claire McCaskill of Missouri said she was comforted and confident he will be a moderating influence on President-elect Trump.
Kelly would be the fifth person to lead the Department of Homeland Security, which includes agencies that protect the president, respond to disasters, enforce immigration laws, protect the nation's coastlines, fight drug smuggling and secure air travel.
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.
Still, Democrats are pressing for more information about several of the nominees who are some of the wealthiest people in America. Said Senate Minority Leader Chuck Schumer, D-N.Y.: "So many of them are billionaires and corporate titans with complex financing holdings that raise the possibility of conflicts of interest, which requires careful scrutiny."
The independent Office of Government Ethics, responsible for ensuring that 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 on Tuesday.
THE REST OF THE WEEK
On Wednesday, hearings will be held for Trump's picks for secretary of state, Rex Tillerson, and transportation secretary, Elaine Chao. Also, a second day of hearings is planned for Sessions.
On Thursday, hearings are scheduled for Mike Pompeo for CIA director, James Mattis for defense secretary, Wilbur Ross for commerce secretary and Ben Carson for Housing and Urban Development secretary.
Mattis retired in 2013 as a Marine Corps general. Because he has been out of uniform for fewer than seven years, the minimum required by law for a former service member to serve as defense secretary, his nomination will require new legislation to override the prohibition. Congress is expected to approve such a waiver law.