Bolivians on Sunday elected a pro-business center-right senator as their new president, ending two decades of socialist rule that left the South American nation deep in economic crisis.

With 97.8 percent of ballots counted, Rodrigo Paz had 54.6 percent of the vote to 45.4 percent for his rival, right-wing former interim president Jorge "Tuto" Quiroga, the Supreme Electoral Tribunal said.

The news was greeted with joy, music and fireworks on the streets of La Paz.

"We came to celebrate the victory with great hope of a new direction for Bolivia," Julio Andrey, a 40-year-old lawyer, told AFP.

Paz, the 58-year-old son of a former president, has vowed a "capitalism for all" approach to economic reform, with decentralization, lower taxes and fiscal discipline mixed with continued social spending.

In his victory address, Paz said Bolivia was "reclaiming its place on the international stage."

Paz also said he had received a congratulatory message from US President Donald Trump, while Secretary of State Marco Rubio said Washington "stands ready to partner with Bolivia on shared priorities."

"After two decades of mismanagement, President-elect Paz's election marks a transformative opportunity for both nations," Rubio said.

Under ex-president Evo Morales, Bolivia took a sharp turn to the left: nationalizing energy resources, breaking ties with Washington and making alliances with China, Russia and fellow leftists in Cuba, Venezuela and elsewhere in Latin America.

After the results were announced, Paz's vice-presidential running mate, Edmand Lara, made a call for "unity and reconciliation" after a bitter campaign.