WASHINGTON — David Wilkins became the U.S. ambassador to Canada Tuesday, surrounded by a throng of South Carolina friends so enormous it shocked the State Department.

“We have a quorum of the South Carolina Legislature here,” said Deputy Secretary of State Robert Zoellick, who swore Wilkins in as the 21st ambassador to Canada — the United States’ and South Carolina’s largest trading partner.

State department officers said Wilkins’ well-wishers constituted one of the largest audiences they had ever seen at an ambassador’s swearing-in ceremony.

Three hundred guests — who might best be described as the people in charge of South Carolina — watched Wilkins swear on his family Bible to uphold the U.S. Constitution and to serve his country faithfully.

The new ambassador ended the ceremony with a speech that caused him and several in his audience to tear up.

“Many of you here today were there in 1980 when I first ran for the House,” said Wilkins, his wife Susan standing behind him. “You believed in us then. You were with us every step of the way. And you’re with us now.

“Thank you for your faith in us.”

The ceremony took place in the gilded Benjamin Franklin Room of the otherwise drab State Department headquarters. South Carolinians sipped champagne on its balcony, which captures views of the Lincoln, Washington and Jefferson memorials.

Looking around the room, state Sen. Scott Richardson, R-Beaufort, remarked: “If something happens today in South Carolina, it’s on its own. Everybody’s here.”

Members of the S.C. House and Senate flew up for the ceremony, as did much of South Carolina’s judiciary, including Joe Anderson, chief justice of the U.S. District Court of South Carolina, and Jean Toal, chief justice of the state Supreme Court.

USC president Andrew Sorensen was there, as was Mack Whittle Jr., president and CEO of Carolina First Corp.

South Carolina’s entire congressional delegation witnessed the ceremony, except for U.S. Sen. Jim DeMint, who was at a policy lunch with President Bush. DeMint’s wife attended instead.

Nancy Thurmond, widow of former U.S. Sen. Strom Thurmond, came with her daughter Julie Whitmer and son-in-law Martin Whitmer.

“I have known them for so, so long,” Nancy Thurmond said of the Wilkins family. “They are a superb choice to be our ambassador and first lady in Canada. We’re so happy and proud of them.”

Canada was represented by Claude Carriere, deputy chief of mission at the Canadian embassy.

President Bush made Wilkins, 58, his nominee for the post in April, even though the Greenville Republican has little international experience. He has led the S.C. House as its speaker for 11 years.

Bush and Wilkins are close, personally. Wilkins ran Bush’s prickly 2000 primary election campaign in South Carolina — a key state in the race for the GOP nomination — and his re-election campaign in South Carolina in 2004.

But Zoellick, who administered the oath to Wilkins, noted that diplomatic and political skills honed in South Carolina should prepare him well for his new job.

As the Republican who first headed up the S.C. House after a generations-old Democratic power base lost its grip on the institution, he developed a reputation for fairness and efficiency.

That will come in handy in Canada, said Zoellick, even though it is considered a great friend of the United States.

The closeness of the two nations — as allies and geographic neighbors — often heightens sensitivities, he said.

Relations have been tense under Bush, with Canada opposing the war in Iraq and defying the U.S. on key trade issues.

“More than most people know, this is an extremely challenging post,” Zoellick said.

Wilkins and his wife flew to Ottawa to take up residence in the American ambassador’s mansion, leaving friends with these words:

“You are only a plane ride or a phone call away.”

Reach Markoe at (202) 383-6023 or lmarkoe@krwashington.com.