In this file photo, US Ambassador to China Terry Branstad (left) speaks to the media at his residence in Beijing, capital of China, June 28, 2017. (PHOTO / XINHUA)

US Ambassador to China Terry Branstad will retire and leave Beijing early next month, the embassy said on Monday.

Branstad, 73 years old and a former governor of Iowa, leaves at a time when relations are strained, notably over bilateral trade, allegations about information security, and the coronavirus pandemic.

A US official familiar with the matter said Branstad will step down to work on President Donald Trump’s re-election campaign.

“I thank Ambassador Terry Branstad for his more than three years of service to the American people as US Ambassador to the People’s Republic of China,” US Secretary of State Mike Pompeo tweeted.

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Over the weekend, US President Donald Trump had said Branstad would return to the US while praising the campaign efforts of the ambassador’s son, Eric Branstad

The Chinese foreign ministry has in the past described Branstad as an “old friend of the Chinese people”.

China’s foreign ministry spokesman Wang Wenbin told a daily news conference that China had not received a notice about Branstad leaving.

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Over the weekend, Trump had said Branstad would return to the US while praising the campaign efforts of the ambassador’s son, Eric Branstad. 

“Eric’s father’s coming home from China because he wants to campaign,” Trump said, in a phone call with supporters of US Senator Joni Ernst, a Republican whose close re-election battle in Iowa could help determine control of the upper house.

With inputs from Bloomberg