(Bloomberg) -- Thailand’s annual budget faces a further delay after an irregularity emerged in the parliamentary vote that was supposed to approve it, signaling yet another obstacle for a struggling economy.

The Constitutional Court will now assess whether the vote in the lower chamber was valid following a request for a ruling from 90 lawmakers, Government Chief Whip Wirat Rattanaset said at a briefing Wednesday in Bangkok.

Outlays from the 3.2 trillion baht ($105 billion) budget were supposed to start Oct. 1, but were delayed by government formation and the legislative process after last year’s general election. Parliamentary assent was completed this month and spending was expected from February.

The irregularity emerged because a lawmaker’s identity card was used during the vote in the lower chamber, but the legislator wasn’t present, said Sorasak Pienvej, the secretary of the House of Representatives. It’s unclear who voted on his behalf, he said.

Government officials were quick to warn about the potential impact of a further hold up. Finance Minister Uttama Savanayana said it would hurt the economy by hampering investment. Deputy Premier Somkid Jatusripitak said the administration is working on a contingency plan.

The prospect of a delay in state projects weighed on some Thai stocks. The SET Construction Services index of builders fell 2.8% as of 3:41 p.m. in Bangkok, making it the stock exchange’s worst-performing industry group.

A time-line for the Constitutional Court to rule on the validity of the parliamentary vote has yet to be laid out. The final stage in the legislative process is royal assent for the budget bill.

The Thai economy may expand 2.8% this year, up from a five-year-low of 2.5% in 2019, based on Bank of Thailand estimates. A surging currency has damaged exports and tourism.

(Updates with matter being referred to court in second paragraph.)

--With assistance from Anuchit Nguyen.

To contact the reporters on this story: Suttinee Yuvejwattana in Bangkok at suttinee1@bloomberg.net;Siraphob Thanthong-Knight in Bangkok at rthanthongkn@bloomberg.net

To contact the editors responsible for this story: Sunil Jagtiani at sjagtiani@bloomberg.net, Yumi Teso

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