President-elect Donald Trump has selected Gov. Terry Branstad (R-Iowa), to serve as ambassador to China. Here's what you need to know about him. (Sarah Parnass/The Washington Post)

President-elect Donald Trump has selected Terry Branstad, the long-serving Republican governor of Iowa, as ambassador to China, a transition official confirmed Wednesday.

Branstad has extensive ties to China and a personal friendship with Chinese President Xi Jinping that dates back decades. If his nomination goes through, the move could help reassure China’s leadership that Trump understands the importance of healthy relations with Beijing.

The Chinese reacted with concern to Trump’s protocol-busting phone call Friday with Tsai Ing-wen, the leader of Taiwan, an island that China considers a rogue province. Trump attacked China repeatedly on the campaign trail, and in a pair of tweets Sunday, over its trade and currency policies, and has criticized the way it has staked its territorial claims in the South China Sea. He has threatened to slap tariffs of up to 45 percent on Chinese goods if Beijing doesn’t “behave.”

The selection of Branstad was first reported by Bloomberg News and confirmed Wednesday by a transition official who requested anonymity because the nomination had not yet been formally announced.

Trump transition spokesman Jason Miller told reporters later Wednesday that Branstad has accepted the president-elect’s offer.

“Governor Branstad obviously is Iowa’s longest-serving governor, someone who has considerable public policy experience but also someone who has a lot of experience and great grasp of trade issues, agriculture issues, has a tremendous understanding of China and Chinese people [and] is someone who very much impressed the president-elect,” Miller said. “It’s very clear that Governor Branstad is someone who will represent our country well on the world stage, and we couldn’t be prouder of this selection.”

China’s Foreign Ministry did not confirm the report but reacted warmly.

“First of all, I would like to say that Mr. Branstad is an old friend of the Chinese people and we welcome him to play a greater role in promoting Sino-U.S. relations,” spokesman Lu Kang said at a regular news conference. “The U.S. ambassador to China serves as an important bridge linking the governments of the U.S. and China. We are willing to work with whomever takes this position to strive for the continued, sound and steady development of bilateral ties.”

Branstad met with Trump in New York on Tuesday and issued a written statement saying that he had enjoyed a “very cordial conversation” with the president-elect and that they had spoken about the transition and the next administration.

Branstad was among the most active Republican establishment figures backing Trump, campaigning regularly with him in Iowa. The governor’s son, Eric Branstad, managed Trump’s general-election campaign in Iowa, one of the contested battleground states. Although Trump finished second in the state’s Republican caucuses, he carried the state in the general election with 51 percent of the vote to Hillary Clinton’s 42 percent.

At a rally in Sioux City, Iowa, Nov. 6, Republican presidential candidate Donald Trump thanked Iowa leaders, including Gov. Terry Branstad, who Trump said would be "a prime candidate to take care of China." (The Washington Post)

Branstad’s move to Beijing, should he be confirmed, would elevate Lt. Gov. Kim Reynolds (R) to the governorship. Reynolds, who has long been considered Branstad’s favored successor, would become Iowa’s first female governor.

Under the Obama administration, experts say, the post of ambassador to Beijing had declined somewhat in importance. China policy was largely run out of the White House, with the president tending to immerse himself in many of the details.

Under Trump, the role could be more significant — and not only because the next president is likely to leave many of the policy details to his advisers. By taking a phone call from Taiwan’s democratically elected leader and continuing to tweet critical comments about China after his election win, the president-elect has shown he will not be bound by diplomatic convention and wants to show he is standing up to China.

Kerry Brown, professor of Chinese studies at King’s College London, said it would be important to have someone in the job who has the president’s ear and can call him up directly.

“There’s definitely going to be problems in the first few months, so you need someone who’s going to get direct access to the president and get the president’s attention,” Brown said. “I get the feeling he’s not going to want piles and piles of briefings. He’s not going to wade through that. In a sense, that makes the personal system, where you can have people speak to him directly, very important.”

Branstad, if he is formally nominated by Trump and confirmed by the Senate, could have his work cut out for him trying to smooth over some of the ripples in the relationship — notably by reassuring the Chinese that the United States does not want confrontation and conflict andstill sees areas for cooperation.

Jie Dalei, an associate professor at the School of International Studies of Peking University, reacted cautiously, saying the appointment could help communication “but is unlikely have too much impact at the decision-making level.”

“At this point, his tweets and remarks certainly have attracted the most attention,” he said. “Compared to that, the appointment of an ambassador to China, though very thoughtful, is unlikely to fix the damage caused by the uncertainty of his tweets and Taiwan call.”

Last month, less than week after Trump’s victory, Branstad paid his seventh visit to China, meeting the country’s agriculture minister as well as officials from Iowa’s sister province, Hebei.

He has described Xi as an “old friend” and, during a 2015 interview with state news agency Xinhua, proudly displayed photographs of two meetings with the Chinese leader.

The first dated to 1985, when Xi made his first trip to the United States as a young agriculture officer from Hebei. The other was from 2012, when Branstad hosted a dinner at the Iowa Capitol for the then-vice president of China.

Branstad also met Xi on a visit to China in 2011. He said the pair spoke for 45 minutes as Xi reminisced about the hospitality he had received when he was in Iowa.

The six-term governor is the longest-serving in American history, and his state voted for Trump by the largest margin for a Republican since Ronald Reagan in 1980.

Iowa has strong economic ties to China; the state is the largest producer of corn and among the largest soybean producers in the United States.

China has been a fast-growing market for Iowa’s agriculture and processed food, with exports from the state up by a factor of 13 between 2000 and 2010 to $6.3 billion, according to Chinese state media.

That fact alone may reassure some people that Trump will not start a trade war with China, since retaliation from Beijing in the shape of reduced soybean and corn imports would hurt not only Iowa but also other Republican-controlled agricultural states.

Branstad was a vocal backer of the Trans-Pacific Partnership, the 12-nation trade deal championed by the Obama administration that Trump has pledged to rip up on his first day in office. Branstad said his state’s large agricultural industry would benefit from the accord, boosting exports of pork, corn and poultry and creating jobs.

The Obama administration said the TPP, which does not include China, was an important strategic initiative to more firmly link the U.S. economy to the Asia-Pacific region as a hedge against China’s growing clout. But Trump denounced the TPP as a threat to American manufacturing workers, and Beijing has touted a rival Asia trade pact that does not include the United States.

Branstad, 70, served as governor of Iowa from 1983 to 1999 and again starting in 2011. Trump will visit the state Thursday on his post-election victory tour.

Two days before the Nov. 8 presidential election, during a rally in Sioux City, Trump called the governor to the stage, calling him “our prime candidate to take care of China.”

Denyer reported from Beijing. David Nakamura and Elise Viebeck in Washington and Luna Lin in Beijing contributed to this report.