US new vehicle sales have been weaker than expected in June and General Motors will have difficulty recording a sales gain for the month, a top GM official told Reuters late on Monday.

“We’re a little weaker than what we expected to be in June,” Paul Ballew, GM’s head of sales analysis, reportedly said in an interview.

Light vehicle sales for the industry will total a seasonally adjusted annual rate of about 16.3 million in June, down from about 16.5 million in June last year, Ballew told the news agency, adding that overall sales weakened in June because May results were far above expectations and pulled forward some sales from this month.

“We expected June to come down a little bit,” he reportedly said.

Reuters noted that industry sales soared to their strongest levels in nine months in May to an annual rate of 17.8 million due to heavy sales incentives and despite soaring petrol prices.

Analysts had generally told the news agency that they expected industry sales to be flat in June, with strong results from some Asian automakers and GM down about 5%.

Reuters noted that, if Ballew’s forecast holds true, it would be the first time the industry has had a year-over-year drop in sales since last July – nevertheless, Ballew and Wall Street analysts expect vehicle sales to strengthen in the second half of the year, due to the firming US economy.

GM’s inventories of unsold vehicles remained unchanged in June from May at above-target levels, Ballew told the news agency.

“We still have to come down about 100,000 units between now and the end of the year,” he reportedly said.

He declined to comment when asked by Reuters if GM would cut its vehicle production in the third quarter to help reduce inventories, but said that the automaker would have more to say on Thursday when it reports June sales.