President-elect Barack Obama has tapped his foreign policy adviser Susan Rice as the U. S. ambassador to the United Nations, Democratic Party officials said.

Rice's nomination to the diplomatic post is expected to be announced Monday during a news conference in Chicago where Obama plans to introduce his choices for his national security team.

Obama's selection of Rice as the U. S. representative to the United Nations is a pick of a forceful advocate of stronger action to end genocide, such as that in Darfur, The New York Times reported Monday.

Obama also indicated he plans to restore the ambassador's post to Cabinet rank, as it was during President Bill Clinton's administration, officials close to the Obama transition team told the Times.

"She's obviously one of Obama's closest advisers, so it underscores how much of a priority he's making the position," said Nancy Soderberg, a senior U. S. diplomat at the United Nations during the Clinton years. "If you look at the last eight years, we obviously need to be more engaged at the U. N. and realistic about what the U. N. can do."