WASHINGTON -- US President Barack Obama on Wednesday tapped UN ambassador Susan Rice to be the next national security advisor, taking the post vacated by Tom Donilon, who has resigned.

Obama made the announcement at a White House ceremony. He said Donilon will depart in July, and will be by his side when he meets Chines President Xi Jinping this weekend in California.

US President Barack Obama announces the appointment of U.N. Ambassador Susan Rice (R) as his new national security advisor, as he stands with current National Security Advisor Tom Donilon (2ndR) and White House aide Samantha Power (L), who was nominated to replace Rice, in the Rose Garden of the White House in Washington, June 5, 2013. [Photo/Agencies]

Obama praised both Donilon and Rice in his remarks. He said Rice is a "consummate public servant," while lauding Donilon, who helped to shape "every single national security policy of my presidency," including the rebalance of US focus to the Asia Pacific region.

Rice, an Obama confidant, lost out in the nomination deliberations of secretary of state due to her involvement in the Benghazi talking points debacle. Obama has complained Republicans have singled her out for attacks.

Although critical of Rice, key Republican senators on Wednesday said they will work with Rice. John McCain, one of Rice's toughest critics, said he disagrees with the appointment of Rice, but he ' ll make every effort to work with her on important issues.

Bob Corker, the top Republican on the Senate Foreign Relations panel, met with Rice prior to her appointment and said he accepted the president's decision.

"I had a very good conversation with Ambassador Susan Rice to let her know I look forward to working with her on shaping important foreign policy and national security issues as she serves in her new role," said Corker.

Obama also nominated Samantha Power, a former national security staffer, to be the next UN ambassador. The nomination of Power needs Senate approval, while Rice's appointment doesn't.