Bernie Sanders is holding off on endorsing Kamala Harris because he wants an influential role in her campaign: report

• Bernie Sanders has not yet endorsed Kamala Harris for the Democratic presidential nomination.
• Though he says he will campaign for her to win, he's holding off on an official endorsement.

Bernie Sanders is one of the few progressive holdouts who has yet to officially endorse Vice President Kamala Harris as the Democratic presidential nominee.

According to The Hill, it's because he wants to play an influential role in her campaign.

Though the independent Vermont senator said Tuesday that he wants Harris to win and will campaign for her victory, he stopped short of an outright endorsement.

He told NBC News: "I look forward to strongly supporting her. But I think if she is going to win, she's going to have to focus a great deal of attention on the plight of the American working class, come up with some very specific suggestions as to how she's going to address the reality that 60% of our people are living paycheck to paycheck."

Sanders had previously encouraged President Joe Biden to stay in the race and, according to The Washington Post, earlier this month he communicated with Biden's aides to pitch progressive policies to add to his second-term agenda.

Once primary rivals, Biden and Sanders ended up collaborating on a series of policy-focused task forces, with some of those recommendations adopted by Biden's 2020 campaign.

Since then, they have teamed up on projects like seeking to lower the cost of prescription drugs.

Sources familiar with the situation told The Hill that Sanders wants similar sway in Harris' campaign.

According to an unnamed Sanders ally who spoke to the outlet, the extent and enthusiasm of his support in the upcoming campaign depends on it, particularly how much Harris chooses to embrace policies impacting working-class voters.

"Right now, you look at where her standing is with a lot of working-class voters, and there's a ton of room for Kamala" to improve, they told The Hill.

The source added: "She hasn't really, since she's been vice president, stated terribly strong views about how she thinks and talks about the economy."

According to The Hill, Sanders' allies believe that the senator, who is 82 and popular with young people and progressives, could help Harris gain support from these demographics.

Other progressive lawmakers, such as Sen. Elizabeth Warren and Reps. Alexandria Ocasio-Cortez and Cori Bush, have already endorsed Harris.

Sanders told NBC News that he needs to see Harris outline a specific plan for the American working class if she's going to win, though he did not specify which policy proposals this might include.

He also told the outlet that her choice of running mate will also factor into his decision to endorse her.

In a comment provided to BI by email, a spokesperson for Sanders said: "The Senator has been very clear that he will do everything in his power to elect Kamala Harris as the next President of the United States."