Former U.S. President Bill Clinton has been tapped as a United Nations special envoy to Haiti, a senior U.N. official said Monday. An official announcement will be made Tuesday, the official was quoted as saying by CNN. The two-term president has traveled to Haiti on several occasions, most recently in March with his wife, Secretary of State Hillary Clinton, and U.N. Secretary-General Ban Ki Moon. At the time, the Clintons voiced optimism at Haiti's potential because of political stability and economic growth after decades of chaos. The Caribbean country is the poorest nation in the Western Hemisphere.