 -- Former FBI Director James Comey is testifying on Capitol Hill today amid a swirl of questions about the Russia investigation and in the wake of his firing.

Here are a look at the key players in the Senate Intelligence Committee testimony:

James Comey, former FBI director

Comey served over three years as the director of the FBI before his firing in May by President Trump, which would lead to Thursday's hearing. Prior to his appointment by President Obama in 2013, he worked as deputy attorney general in the Bush administration and U.S. attorney for the southern district of New York for almost two years. In written testimony released Wednesday, he wrote that Trump asked for his loyalty during private meetings and that he assured the president that he wasn't personally under investigation.

Sen. Richard Burr, R-N.C., chair of the Senate Intelligence Committee

After serving five terms in the House, Burr moved to the Senate, where he currently is serving his second terms. He has been an adamant support of military families and veterans, and prioritizes protecting American security through his work on the Senate Intel Committee. During Wednesday’s hearing of Coats and company, he demanded answers, saying: “At no time should you be in a position to come to Congress without an answer.”

Sen. Mark Warner, D-Va., vice chairman of the Senate Intelligence committee

The Democrat was elected to his Senate post to represent the state of Virginia in 2008, and is currently serving his second term. In the Senate, Warner has a record of reaching across the aisle to increase government accountability and improve job creation. Prior to his post in the Senate, Warner served as the Governor of Virginia from 2002 to 2006. Warner was disappointed with the answers he received Wednesday from DNI Coats and Admiral Roberts. He emphasized the gravity of this investigation, comparing it to Watergate when he said on Morning Joe: “We are in a land that we’ve never visited before, even back beyond the ‘70s.”

Feinstein is a 24-year senate veteran who is the former chairman of the Senate Intelligence Committee. Feinstein, 83, is the oldest member of the senate, and was quick to question the White House's rationale for firing Comey last month, immediately asking publicly whether the dismissal was tied to the Russia investigation.

A first term senator, just five months into her term, Harris is the former attorney general of California and district attorney of San Francisco. Her highly-publicized senate victory in the country's most populous state and willingness to take on high-profile issues early into her senate tenure has led to speculation she could be eyeing a bid for the presidency in 2020.

Rubio is serving his second term in the Senator, previously serving as Speaker of the Florida House of Representatives. In the 2016 Republican presidential primary, Rubio ran a competitive campaign but eventually ceded to President Trump. During Wednesday’s hearing, Rubio responded to Coats’ refusal to answer by saying that “the American people deserve to know” the validity of media claims surrounding the investigation.

Cotton is serving his first term in the Senate, having been elected in 2014. Before becoming Senator, Cotton served in the military in Iraq and Afghanistan and held one term in the U.S. House of Representatives. Cotton has worked alongside Trump to craft policy that aligns with both traditional Republican beliefs and Trump’s unique rhetoric.