The deterioration of the political system contributed towards the rise of a loose confederation of indigenous social movements, the MAS and others parties, with the head of the MAS, Evo Morales, a former cocalero, as leader. In the elections of December 2005 Evo Morales and MAS obtained a comfortable victory reaching 54% of the electorate's votes, becoming the first Native Bolivian president in history.
On 1 May 2006, Evo Morales delivered on his promises to nationalize most of Bolivia's natural gas fields, which many indigenous Bolivians had demanded for years. Troops were sent in to occupy the gas fields and take back control from foreign companies that same day. Many were operated by Petrobras, Brazil's largest energy company, and this political development was expected to strain relations between Morales and Brazilian president Luiz Inácio Lula da Silva. On 29 October 2006, the Morales government signed agreements with eight foreign gas firms including Petrobras, to give the Bolivian national gas company a majority stake in the gas fields, bringing the nationalization to completion.
In late August 2007, the MAS purged the Constitutional Tribunal of magistrates that voted earlier in the year against Morales' move to fill Supreme Court vacancies while Congress was in recess. The purge dismantled the outlet for arbitration between branches of government.
On 4 May 2008, autonomy referendums were held in four eastern departments, in which they declared themselves autonomous from the central government. All four referendums passed. Evo Morales deemed this referendum illegal. Turnout was as low as 70%.
In February 2009 a new constitution was enacted by Evo Morales. This gave Bolivians of indigenous descent more economic and political rights.