US Secretary of State John Kerry choked back tears Wednesday, saying he had been "humbled" by the outpouring of support for his wife, who remains in hospital after an apparent seizure.
"Teresa is doing better, under evaluation and we hope improving," Kerry said, opening two days of talks with senior US and Chinese leaders.
Teresa Heinz Kerry, 74, has been in hospital since displaying seizure-like symptoms on Sunday while the couple were vacationing with their family at their home on Nantucket Island, off Cape Cod, Massachusetts.
Kerry had flown late Tuesday to Washington from Boston, where his hospitalized wife is undergoing tests, to host a dinner with senior Chinese leaders, including Vice Premier Wang Yang and State Councilor Yang Jeichi.
At Wednesday's opening of the talks, he thanked friends and colleagues for the "remarkable outpouring of good wishes," adding "we are very, very humbled by the expressions of support."
"I think she's coming along and I know when she's able to she'll thank everybody herself," said Kerry, his voice breaking with emotion as he paused to compose himself.
The top US diplomat was planning to cut short his Washington trip and return to Boston later Wednesday to be with his wife. He will be represented at the talks by Deputy Secretary William Burns, the State Department said.
Kerry, 69, the 2004 Democratic presidential candidate, had been celebrating the July 4 holiday weekend with his family on his first long break since becoming secretary of state in February, when his wife fell ill.
After being at his wife's bedside since she was rushed first by ambulance to a local Nantucket hospital, Kerry traveled back to Washington to launch for the long-planned talks with Chinese officials.
Heinz Kerry, a former interpreter at the United Nations, and Kerry have been married for 18 years. They have 5 children between them.
Heinz Kerry was previously married to senator Henry John Heinz, heir to the Heinz ketchup fortune, who was killed in a helicopter crash in 1991.
Doctors have so far ruled out a stroke, heart attack or brain tumor as the cause of her illness.
A committed environmentalist like Kerry, they first met at an Earth Day summit in 1990. They then met again two years later in Rio for an Earth Day event, after Heinz's death.