U.N. Ambassador Susan Rice is joining the White House as National Security Adviser, following Tom Donilon’s resignation from the post. Jansing & Co. will discuss with Senator Johnny Isakson, R-Georgia, NBC’s Kasie Hunt and The Washington Post’s Dana Milbank. President Obama is scheduled to make the announcement at 2:15 PM ET today in the Rose Garden. A White House official confirmed to NBC News that Samantha Power will be nominated to fill Rice’s position as U.S. Ambassador to the U.N.