United Nations ? U.S. Ambassador John Bolton urged U.N. member nations Tuesday to start negotiations to resolve major differences on a proposal to reform the United Nations and reduce poverty that world leaders are supposed to adopt at a U.N. summit in three weeks.

In a letter to ambassadors from the 190 other U.N. member states obtained by The Associated Press, Bolton said “time is short” and there is a need for flexibility “to maximize our chances of success.”

The latest draft of the proposed final document is nearly 40 pages long, and deep divisions remain on key issues. Among them: defining terrorism, overhauling U.N. management and replacing the ineffectual Commission on Human Rights, preventing future genocides, and expanding the U.N. Security Council.

Last week the United States made extensive comments and proposals for changes in the latest blueprint put together by General Assembly President Jean Ping.