LISBON, Portugal (AP) — The swearing-in of Portugal’s new Socialist government may be delayed until mid-March, six weeks after the general election, due to a snafu over voting from abroad.

In a ruling late Tuesday that embarrassed politicians, Portugal’s Constitutional Court voided around 80% of mail-in votes cast by Portuguese living in the rest of Europe and ordered a rerun of January’s balloting in those areas.

A gentleman’s agreement between the political parties represented in the Portuguese parliament before the Jan. 30 election scrapped the requirement for voters to send a copy of an official identity document with their postal ballots.

But the 13 judges at Portugal’s highest court said that decision was “grossly illegal” because it contravened electoral law. The court said more than 157,000 votes that were unaccompanied by an ID document were invalid and that the election at 139 voting stations across Europe must be rerun.

The decision didn’t only cause embarrassment. It also had practical repercussions, including delaying the 2022 state budget until June.

Incoming Prime Minister António Costa, who had expected to take office next week, apologized to voters. He said the episode should “serve as a lesson” for politicians to write better laws.

The center-left Socialists’ landslide win is not in doubt, however, as the party collected 117 seats in the 230-seat parliament through votes cast in Portugal.