RIO DE JANEIRO (Reuters) -Former Brazilian President Jair Bolsonaro's future in office hung in the balance on Thursday, as the country's federal electoral court (TSE) began a trial that could leave him in the political wilderness for nearly a decade.

Bolsonaro, a far-right nationalist who in October narrowly lost Brazil's most fraught election in a generation, stands accused of abusing his presidential power last year when he summoned foreign diplomats to publicly vent unfounded attacks on the country's electronic voting system.

Bolsonaro's accusers have also included in the charges against him a draft memo for how to overturn the election, found at the house of his former justice minister.

The outlook appears bleak for Bolsonaro, a career politician who was until recently Brazil's most powerful man.

He still retains significant backing from his core supporters, but many in Brazil have tired of his scorched-earth politics that culminated in the storming of government buildings in Brasilia on Jan. 8 by thousands of his supporters.

Luiz Inacio Lula da Silva, Bolsonaro's fierce leftist rival who won last year's election, is meanwhile starting to reap the benefits of an improving economy.

Tarcisio Vieira, Bolsonaro's lawyer, told Reuters this week that his polarizing client faces an "unfavorable" climate from the country's media and the political and judicial classes.

On Thursday, Vieira told the court that if Bolsonaro misspoke during the meeting with ambassadors, he should be fined rather than losing his right to stand in elections.

In an opening speech, Vieira said the case against Bolsonaro was "doomed to failure." The purported link with the Jan. 8 riots was "inventive and fallacious," he added.

If the TSE rules against Bolsonaro, the 68-year-old could find himself unable to run for public office until 2030. That may not be the end of his troubles, though, as he also faces multiple criminal investigations that could put him behind bars.

Much of Brazil appears eager to move on from the fire and brimstone of the Bolsonaro years.

Some of his former conservative allies are now publicly pinning their hopes on other right-wingers - such as Sao Paulo Governor Tarcisio Freitas and Minas Gerais Governor Romeu Zema - while others in the Bolsonaro clan, including his wife and lawmaker sons, may also harbor their own presidential ambitions.

(Reporting by Gabriel StargardterEditing by Brad Haynes, Chizu Nomiyama and Rosalba O'Brien)