FILE - In this Dec. 18, 2007 file photo, Argentina's President Cristina Fernandez, left, waves to photographers as Brazil's President Luiz Inacio Lula da Silva, center, talks to Venezuela's President Hugo Chavez during the official photo at the Mercosur Summit in Montevideo, Uruguay. Already the Western Hemisphere's longest-serving president, Chavez has helped lead the charge of incumbents who have secured constitutional changes and stayed on for multiple terms, overturning provisions that had barred or limited re-election. Presidents in Argentina, Bolivia, Brazil and Colombia have won re-election since 2006. (AP Photo/Marcelo Hernandez, File)
