MEXICO CITY (AP) -- Enrique Pea Nieto has taken the oath of office as Mexico's new president, bringing the old ruling party back to power after a 12-year hiatus.
His Institutional Revolutionary Party ruled for 71 years with a mix of populist handouts, graft and rigged elections before being voted out and replaced by the conservative National Action Party in 2000.
Pea Nieto has promised to govern democratically with transparency.
His swearing in was marred Saturday by protesters outside the Congress lobbing homemade bombs and firecrackers and shouting: "Mexico without the PRI!"
Before the swearing in, leftist congressmen inside the chambers demanded to know what was going on in the crowds and urged police to use restraint.
Congressman Rafael Huerta of the Labor Party urged the new government to protect the people.