Al Gore speaks during the 2015 SXSW Music, Film + Interactive Festival at Austin Convention Center in March.  (Photo: Travis P Ball/Getty Images for SXSW)

Will former Vice President and environmental activist Al Gore run for President again? Some insiders say he might.

On Thursday, Buzzfeed reported that Mr. Gore supporters have been discussing the possibility of a run for president in 2016. The revelation is a sign that “top Democrats have serious doubts that Hillary Clinton is a sure thing,” Buzzfeed reporter Andrew Kaczynski wrote.

“They’re figuring out if there’s a path financially and politically,” an unnamed Democrat told Mr. Kaczynski. “It feels more real than it has in the past months.”