“What I hear [of] his agenda now I don’t support,” Manchin said, adding that his support would depend on Sanders’ agenda. “He knows that ... We have a different way of doing things and you know I’m not going to change who I am. I am who I am, and I’ve always been that way.”

If Sanders were to win the presidency, and Democrats take back the House and Senate, Manchin and other moderates would likely play a crucial role in determining whether or not his legislative agenda could succeed.

In his interview with CNBC, Sanders argued that Manchin would support his policy plans because he would take his message to West Virginia. Sanders won the Democratic primary in West Virginia in 2016.

“Your average politician sits around and he or she thinks, ‘Let’s see. If I do this, I’m going to have the big money interests putting 30-second ads against me,” Sanders told CNBC. “But now they’re going to have to think, ‘If I don’t support an agenda that works for working people, I’m going to have President Sanders coming to my state and rallying working-class people.’”

But so far Manchin appears unmoved. He reiterated he does not support “Medicare for All” - Sanders’ signature campaign issue which would eliminate private health insurance and place everyone under a single government-run health insurance plan.

The West Virginia senator would rather focus on addressing issues with Obamacare.

“It doesn’t work,” Manchin said, of Medicare for All. “Basically we can’t pay for ‘Medicare for some’… I think we ought to be fixing the Affordable Care Act. And we got two bills that would do it and reduce the private pay immensely. So yeah, we just have a difference on that.”