India’s second-highest ranked election commission official has resigned, the justice ministry said, days before the expected announcement of general elections in which Prime Minister Narendra Modi will seek a third term.

Arun Goel resigned on Saturday, leaving the Election Commission of India with only one of its three top officials to conduct what will be the largest exercise of the democratic franchise in human history.

Nearly a billion people are eligible to cast ballots in the elections, likely to be held in April-May.

The Ministry of Law and Justice said Indian President Droupadi Murmu had accepted Goel’s resignation, but did not cite a reason for his departure.

The NDTV news network said Goel had resigned due to “personal reasons”, citing sources.

Another official had retired last year and the position has not yet been filed.

The dates for the election, conducted in several phases, are likely to be announced next week, according to local media reports.

K.C. Venugopal, general secretary of the main opposition Congress party, said Goel’s resignation was a concern.

“It is deeply concerning for the health of the world’s largest democracy that Election Commissioner Mr Arun Goel has resigned on the cusp of the Lok Sabha (parliamentary) elections,” he said in a social media post.

“There is absolutely no transparency in how a constitutional institution like the ECI has been functioning and the manner in which the government pressurises them.”

Several opinion polls have indicated an easy win by Modi and his Hindu nationalist Bharatiya Janata Party in the general election.

A Pew survey last year found Modi was viewed favourably by nearly 80 per cent of Indians.

A poll of urban voters conducted by YouGov in February showed the BJP comfortably leading India’s manifold opposition parties in every measured age and gender demographic.