Kerry, 75, and Biden, 76, served together in the U.S. Senate, representing Massachusetts and Delaware respectively.
Although Kerry stopped short of endorsing Biden, his comments raise the prospect that he will support the former vice president over Elizabeth Warren, a senator from his home state.
Kerry spoke to Sky News while appearing at the Our Ocean Wealth summit in Cork, Ireland.
During an appearance in November at Harvard’s Institute of Politics, Kerry left open the possibility of running in 2020, saying, “I’m not taking anything off the table.”
At the time, he said he would be willing to support another candidate if he thought that person could win and address issues he cares about. “But . . . I don’t see the person yet that I’m prepared to say that about,” Kerry added.