Néstor Kirchner's center-left Front for Victory ticket during the 2005 legislative elections. Securing a seat in the Chamber of Deputies (lower house of Congress), he forfeited it at the behest of the President, who requested that he stay on as Director of ANSeS. Remaining at the post two more years, he oversaw the voluntary conversion of several million private pension accounts to the ANSeS' aegis when this choice was made available in December 2006. Mayor of Tigre and Cabinet Chief Massa was elected Mayor of the Paraná Delta partido of Tigre in October 2007. That year's elections also brought President Néstor Kirchner's wife, Senator Cristina Kirchner, to the Presidency. Enjoying large majorities in Congress, her administration suffered its first major setback when her proposals for higher agricultural export taxes were defeated on July 16, 2008, with Vice President Julio Cobos's surprise, tie-breaking vote against them. The controversy helped lead to the July 23 resignation of Alberto Fernández, the president's Cabinet Chief, and to his replacement with Sergio Massa who, at 36, became the youngest person to hold the influential post since its creation in 1994. He was persuaded to run as a stand-in candidate (who, after the election, would cede his new seat to a down-ticket name on the party list) for the ruling Front for Victory (FpV) ahead of the June 2009 mid-term elections. Massa, however, enlisted his own candidates (including his wife) for the Tigre City Council under his own ticket, and its success in these city council races distanced him from others in the FpV. Massa had, moreover, harbored differences with the president over a number of policies, including the nationalization of loss-producing private pension funds, the use of the INDEC bureau to understate inflation data, and the vast regulatory powers granted to Commerce Secretary Guillermo Moreno. Following the FpV's narrow defeat in the Chamber of Deputies mid-term races, Massa tendered his resignation to the President, effective July 7. Massa, who appointed the city council president as provisional mayor while he served as the president's cabinet chief, returned to his office of Mayor of Tigre on July 24. He was investigated along with other officials for the illegal retention of "repayments" of nonexistent loans from the pensions of about 17 thousand retired while he was director of the ANSES Break with the Kirchners In 2010, Massa joined a group of eight Buenos Aires Province mayors in calling