NOMINATION AMID CONTROVERSY

Obama also seized the moment to allude the recent controversies over counter-terrorism efforts and protection of individual privacy, sparked by disclosures of two classified phone and internet surveillance programs.

"And as we have seen in recent days this work of striking a balance between our security but also making sure we are maintaining fidelity to the values we have cherished is a constant mission," said Obama.

US President Barack Obama shakes hands with FBI Director Robert Mueller (L) after presenting James Comey (not pictured), a Republican who served in the Bush Justice Department, as his choice to replace Mueller during a Rose Garden announcement at the White House in Washington, June 21, 2013. [Photo/Agencies]

The president and several intelligence officials have argued that those secret surveillance programs have helped to thwart terror plots.

Last week, Mueller defended the two classified phone and internet surveillance programs before lawmakers and vowed to hold the leaker responsible for the disclosure.

He told the lawmakers during a hearing that the disclosures have caused "significant harm to our nation and to our safety."

He even suggested that if the surveillance programs had been in place before the September 11, 2001 terrorist attacks, they might have helped to yield evidence of connections of the participants and derail the plan.

The Guardian and The Washington Post reported last Thursday that the National Security Agency and the FBI had been secretly tapping directly into the central servers of nine US internet companies, extracting audio, video, photographs, e-mails, documents and connection logs that enable analysts to track a person's movements and contacts over time.