ChemChina has extended its $43 billion offer for Swiss agrochemicals giant Syngenta by more than a month as it waits for regulatory approval. The main offer period has been extended to Jul. 18 with potential further extensions to be determined, said CNAC Saturn, a subsidiary of ChemChina. The previous deadline was May 23.

The Chinese company is expecting to complete the deal by the end of the year. According to the offer prospectus, ChemChina may continue to extend the main offer period until Nov. 23, if regulatory approval has not been granted by then. The deal requires that at least 67% of Syngenta shares are tended for the transaction to conclude.

As well as approval from antitrust authorities in Europe and elsewhere, the toughest scrutiny is expected to come from the US, notably the Committee on Foreign Investment in the United States (CFIUS). ChemChina and Syngenta voluntarily initiated a review by CFIUS following their announcement of the proposed merger in February.

According to media reports, the US Department of Agriculture (USDA) has agreed to join the US state panel that is reviewing the takeover. The move was said to have occurred after lawmakers wrote in March to Treasury Secretary Jacob Lew, who is also the chair of CFIUS, requesting that the USDA be involved so that any potential impact on domestic food security could be better assessed.

ChemChina’s takeover of Syngenta would be the largest foreign acquisition ever by a Chinese company.