Bolivia’s new interim president has pledged to hold a new election as soon as possible and condemned “revenge” acts by disgruntled supporters of fallen leader Evo Morales who resigned after protests over a disputed vote.

The senate vice-president, Jeanine Áñez, 52, assumed the interim role late on Tuesday with a Bible in her hand after Morales took refuge in Mexico following the end of his 14-year socialist rule.

“God bless you and allow us to be free and to hold transparent elections soon,” she tweeted on Wednesday in a message to the country’s young people.

Her arrival at the presidential palace faces an immediate challenge from lawmakers loyal to Morales who hold a majority in parliament and have threatened to hold a rival session to nullify her appointment.

After weeks of violent protests over alleged election rigging and then Morales’s resignation, the highland capital La Paz was calmer on Wednesday, though dozens of his supporters protested outside looking to block access to the palace.

In 48 hours of turmoil at the weekend, mutinous police joined marches, allies deserted Morales, the Organization of American States (OAS) declared his re-election was manipulated, and the military urged him to quit.

From Mexico, Morales has stayed defiant, tweeting that Áñez’s “self-proclamation” was an affront to constitutional government. “Bolivia is suffering an assault on the power of the people,” he wrote.

Supporters, including a teaching union, planned rallies for Morales, Bolivia’s first indigenous president who was beloved by the poor when he took power in 2006.

Opponents say pressure had built to a point of no return after increasing evidence of tampering with the October vote, and that Morales had gone against the will of the people by seeking a fourth term.

Bolivia’s largest union threatened a widespread strike unless politicians could restore stability, while a coca farmers’ union official and a lawmaker close to Morales called for protests until he returned to finish his mandate in January.

Áñez met on Tuesday night with the police and military, urging them to ensure peace.

“What a shame revenge continues,” she tweeted to one lawmaker who said his house had been attacked by supporters of Morales’s Movement for Socialism (Mas).

Áñez, a conservative Christian, cuts a very different figure from Morales, who was Bolivia’s first indigenous president in modern times, and she immediately tried to set herself apart from her predecessor.

Wearing the presidential sash of office, she greeted supporters at an old presidential palace instead of the modern 26-storey presidential office with a heliport that was built by Morales and that his foes had criticized as one of his excesses.

She also carried a Bible, which had been banned by Morales from the presidential palace after he reformed the constitution and recognized the Andean earth deity Pachamama instead of the Roman Catholic church.

Bolivia’s crisis has divided international reaction, with leftwing allies echoing his allegations of a coup, and others cheering his resignation as good for democracy.

Conservative-led Brazil and the UK both congratulated Áñez.