The U.S. and China have no choice but to conclude ongoing trade negotiations, most likely in the next month or so, former U.S. ambassador to China Max Baucus said Thursday.

"The talks will conclude. They have to," Baucus told CNBC's Martin Soong at the Boao Forum for Asia in the Hainan province of China. "U.S, China, we're so closely joined at the hip economically, we got to get this thing done."

"There's some feeling here maybe — by the end of April, maybe a little longer — but we'll get it done," Baucus said, noting that otherwise, U.S. stock markets and China's already slowing economy would be negatively impacted.

President Donald Trump has often compared his political success with the U.S. stock market, which has pushed higher over the last 10 years in the longest bull market in history. Meanwhile, official figures showed China's economy grew at its slowest pace last year since 1990, and authorities expect the rate to slow further this year.