John Kerry had a one-word answer when asked his message for President Donald Trump: "Resign."

The former secretary of State and Democratic U.S. senator from Massachusetts made the declaration while speaking on a CNBC panel at the World Economic Forum in Davos, Switzerland. Kerry, who lost in his bid to become president in 2004, first hesitated to answer the question, lamenting that Trump "doesn't take any of this seriously" before calling for his resignation.

A White House spokesman did not immediately respond to CNBC's request for comment on Kerry's remark.

Trump, along with a delegation of government officials, was scheduled to travel to Davos but canceled due to the ongoing partial shutdown of the government. The shutdown has entered its second month with no resolution in sight, as 800,000 furloughed federal workers are set to miss a second paycheck this week.