Brazil's President Michel Temer gestures during opening ceremony of the 20th conference of the march in defense of the municipalities, in Brasilia, Brazil May 16, 2017. REUTERS/Ueslei Marcelino

BRASILIA (Reuters) - The head of Brazil’s top electoral court said on Tuesday that justices would again next month take up a case that could annul the 2014 election on charges of illegal campaign financing and even unseat President Michel Temer.

Justice Gilmar Mendes, who also sits on Brazil’s supreme court, said the trial would restart June 6 and that it could take up to a year before a verdict is reached.

It had been halted in early April so new testimony and arguments by the defense could be heard.

The case is a potential threat to Temer, who in 2014 was elected as vice president to President Dilma Rousseff, and could potentially be tossed from office depending on the full Supreme Electoral Court’s ruling.

Temer took over the presidency a year ago when Rousseff was impeached on illegal budgetary maneuvers. Dilma and her supporters labeled it a “coup” orchestrated by Temer and his allies in an attempt to halt a sweeping political kickback investigation.

Despite the potential threat against Temer, Mendes, who is strongly linked to a party that is allied with Temer’s, told Reuters in a March interview that the president would not necessarily lose power if the election were annulled because he was not the head of the ticket.

Prosecutors allege that Rousseff’s Workers Party received millions in illegal campaign donations as part of a wider corruption scheme that involved billions in bribes paid by large construction firms in return for winning lucrative contracts from state-run oil company Petrobras.

Executives from the Odebrecht construction group have said in plea bargain testimony that they made 300 million reais ($97 million) in illegal campaign contributions to Rousseff’s 2014 re-election campaign, which Rousseff strongly denies.

But they said Temer had not requested donations himself, which could bolster his lawyers’ argument that he was not responsible for the illegal payments.