Bolivia's Constitutional Court on Tuesday upheld the appointment of Janin Anez as interim president to fill a power vacuum, while outgoing President Evo Morales called it "the most insidious coup in history".
A statement from the court to support the 52-year-old's appointment came after a confirmation hearing in Congress failed to secure a quorum.
The court cited a 2001 constitutional declaration that the executive branch should not be suspended, so that the next in sequence would be "de facto" presidency.
Anniz, the second vice president of the Senate, is constitutionally empowered to take over the presidency after the vice president, the presidents of the Senate and the House of Representatives, who all resigned with Morales.
For his part, Morales condemned what he called "the most malicious and aggressive coup in history", after Anniz declared herself interim president.
In a Twitter tweet from his exile in Mexico, Anniz described him as a "right-wing senator inciting coup".
Blood injection
"She declared herself an interim president without a quorum, surrounded by a group of accomplices and supported by the armed forces and police who oppress the people," Morales said.
He said he learned from a security source that one of the parties allocated a financial reward of fifty thousand dollars for those handed over to what he called "coup".
Morales said Mexican President Andres Manuel Lopez Obrador had saved his life by granting him political asylum.
He added that "the coup began after we won the first round of the elections held on October 20 last, unfortunately some police participated in this civil political coup."
Morales pointed to the organization of violence against the families of officials (in his government) in order to force them to resign, and that he decided to resign in order to avoid clashes and bloodshed.
The Bolivian authorities put the death toll from the violence that followed the announcement of the results of the presidential elections last October reached seven.