Brennan, 57, currently is the Deputy National Security Adviser for Homeland Security and Counter terrorism.
"I have many questions and concerns about his nomination to be Director of the Central Intelligence Agency, especially what role he played in the so-called enhanced interrogation programmes while serving at the CIA during the last administration, as well as his public defense of those programmes," Republican Senator John McCain said in a statement shortly after Obama announced his nominations.
"I plan to examine this aspect of Mr Brennan's record very closely as I consider his nomination," Republican Senator McCain said.
In a statement, the American Civil Liberties Union (ACLU) urged the Senate not to confirm his nomination.
"The Senate should not move forward with his nomination until all senators can assess the role of the CIA and any role by Brennan himself in torture, abuse, secret prisons, and extraordinary rendition during his past tenure at the CIA, as well as can review the legal authorities for the targeted killing programme that he has overseen in his current position," Laura Murphy, director of the ACLU's Washington Legislative Office, said.
"This nomination is too important to proceed without the Senate first knowing what happened during Brennan's tenures at the CIA and the White House, and whether all of his conduct was within the law," she said.
However, the White House was quick to dismiss those concerns.
"One, at the time, Mr Brennan wrote a letter in which he made clear that he opposed so-called enhanced interrogation techniques. And two, for the past four years, John Brennan has served as this President's chief counter terrorism adviser, and it is this President who banned torture as one of his first acts in office," White House Press Secretary Jay Carney said.
Washington: Rights bodies and lawmakers in the US on Tuesday raised concerns over the nomination of John Brennan by President Barack Obama as the next Director of the CIA, questioning his role in the so-called enhanced interrogation programmes, even as the White House defended the choice.
First Published: Tuesday, January 08, 2013, 14:10