[1] He started his political career as member of the Radical Civic Union party (UCR), becoming Governor of the Province of Mendoza in 2003.

His popular prestige got a big boost in 2008, when the Senate was voting on a controversial and contentious law to increase taxes on grain exports.

This led to strong criticism from his party, who deemed him a traitor, and approval from sectors of the population that opposed the government.

After his election, Cobos became a leading supporter of Peronist President Néstor Kirchner in Radical ranks, taking a more left-wing position.

[2] Mendoza's constitution does not allow re-election; however Cobos supported Celso Jaque to take office in 2007 on the same slate as Kirchner.

Cobos was asked by Cristina Fernández de Kirchner to stand as her running mate in 2007 heading the Front for Victory slate.

[5] Cobos criticized her decision to nationalize more than $25 billion in private pension funds as premature and would only create more doubts among investors about the stability of Argentina's investment climate.

[9] In July 2010, he returned to the Radical Civic Union headquarters, where he was greeted by party officials Gerardo Morales, Ernesto Sanz, Ricardo Alfonsín and Oscar Aguad.