Left-wing Latin American leaders have congratulated Bolivian President Evo Morales, who has claimed victory and a third term in office after presidential elections held on Sunday.
The presidents of Argentina, Nicaragua, Uruguay and Venezuela expressed their good wishes to Mr Morales.
Exit polls show him on 60%, well ahead of his closest rival's 25% of the vote.
To avoid a run-off, he must win 50% of valid votes, or 40% if that includes a 10-point lead over his nearest rival.
'Carry on winning'
Nicaraguan President Daniel Ortega said Mr Morales's lead in the exit polls was proof of "the vigour of the liberation process in the region".
Argentine President Cristina Fernandez de Kirchner and Uruguayan leader Jose Mujica both called Mr Morales to personally congratulate him.
Venezuelan President Nicolas Maduro wrote a series of messages on his Twitter account (in Spanish) celebrating Mr Morales's lead.
"Evo, a great victory of the South American homeland, from Venezuela we send you a hug and congratulations, let's carry on winning!" he wrote.
Salvadorean President Salvador Sanchez Ceren tweeted that the election "strengthens democracy, Bolivia continues building hope for Latin America and the world".
President Morales told cheering supporters at the presidential palace in La Paz that "this win is a triumph for anti-imperialists and anti-colonialists".
He dedicated "this triumph" to the Cuban revolutionary leader Fidel Castro and Venezuela's late president, Hugo Chavez.
Mr Morales has overseen strong economic growth since taking office in 2006, using Bolivia's commodity wealth to reduce poverty levels.
But he has been criticised for failing to halt corruption.
Analysis: Ignacio de los Reyes, BBC News
Evo Morales became the first indigenous president in 2006 and is even more popular now, and not only among his Aymara ethnic group.
He won the trust of many thanks to Bolivia's good economic performance. Supermarkets, cinemas and restaurants are popping up everywhere.
The new cable car in La Paz is perhaps the best example of the changing times in Bolivia, which remains one of the poorest countries in the region.
It connects La Paz with the satellite city of El Alto, home to thousands of migrants. There, a monument to Che Guevara sits next to a brand new shopping centre, surrounded by thousands of poorly built stalls selling counterfeit products.
Mr Morales's critics have accused him of using millions of dollars in government cash to fund his re-election campaign and say that this has helped create a fractured opposition.
They say he has also introduced measures which are harmful to the environment.
Heading into the elections, Mr Morales's closest rival was Samuel Doria Medina, who vowed to clean up the judiciary if elected.
Exit polls suggest he is trailing well behind Mr Morales, with 25% of the vote.
Mr Morales's party, the Movement Toward Socialism, is expected to make gains and win a strong majority in Congress.
If Mr Morales maintains his two-thirds control of the Senate and assembly, this could could allow him to alter the constitution to permit a fourth term in office.
He has already benefited from a court ruling that permitted him to run for a third term.