“It would be an uphill fight, almost like climbing a wall,” former senator Bob Kerrey (D-Neb.) said in an interview. “He would be running against someone who simultaneously has two television shows based on her. She is a political figure with such remarkable strength ahead of the campaign, unlike anything I’ve seen in my lifetime. The question is whether all the minds of those who would vote at the convention are closed.”

Kerrey, who in 1992 battled for the Democratic nomination that Bill Clinton eventually won, has been urging Webb to challenge Hillary Clinton in 2016. Over phone calls in recent weeks, the two friends — Kerrey is also a decorated Vietnam veteran — have concluded that Clinton could be vulnerable. They believe Webb could win over activists in early primary states who are uncomfortable with Clinton’s vote as a senator in 2002 to authorize war in Iraq and her support for the strategy President Obama is pursuing to fight the Islamic State.

Webb “would speak forcefully and have tremendous credibility on the issue of war and peace,” Kerrey said, and with war raging, some Democrats may seek a contrarian voice to counter the hawkish impulses that have shaped Clinton’s worldview.