In an interview with Japan's TV Asahi, Mr. Clinton said he did not know whether his wife has any plans to one day run for the White House.
"I don't know if she'll run or not," he told the network, but added, "She would make an excellent president, and I would always try to help her."
Also Sunday, a powerful Democratic senator said Sen. Clinton would be the toughest candidate to beat if she decided to run for president.
"I think she'd be incredibly difficult to beat," said Sen. Joe Biden, D-Del., on NBC's "Meet the Press." "I think she is the most difficult obstacle for anyone being the nominee."
Hillary Clinton has said she plans to run for re-election as New York senator in 2006. Speculation has periodically surfaced, however, that the 57-year-old former first lady may have her sights set for the presidency in 2008.
Results from a U.S. poll released last week showed that six in 10 American voters believe the United States is ready for a female president.
Fifty-three percent thought Hillary Clinton should try for the job, according to the survey by the Siena College Research Institute and sponsored by Hearst Newspapers.
"If she did run and she was able to win, she'd make a very, very good president," Mr. Clinton said Sunday. "I think now she's at least as good as I was."
Mr. Clinton was in Japan on a three-day visit to attend an international forum organized by the Asahi newspaper and to promote a Japanese-language edition of his best-selling memoir "My Life."
Biden said Sen. Clinton "is likely to be the nominee," and added, "I think Hillary Clinton is able to be elected president of the United States."
Biden also said he is thinking about running again, 20 years after his first failed bid for the White House because "there's a lot at stake."