Venezuelan President Hugo Chavez is open to working more closely with the next US president, he said just days after Barack Obama became the Democratic Party's presumptive White House nominee.  "I would like to prepare the groundwork, whoever the new (US) president is, for us to work together on a global war on hunger, to save the world from the crises of nutrition, energy and climate," Chavez said during a ruling party function.  Now that the names of the likely Democratic and Republican party candidates for the top job in Washington are known, "they have begun using my name in the domestic campaign," the leftist Venezuelan leader said.  "One of them said he would talk with Chavez and another said he wouldn't," he added, in reference to Obama and his Republican opponent John McCain, respectively.