Sen. Bernie Sanders, the longest-serving independent member of Congress in American history, plans on relying on his gut as to whether he will run for president in 2016.

"Before I make that decision, I have to develop a sense in my own gut as to whether or not there is the grassroots support across this country," the Vermont senator told ABC News during an interview in Iowa. "My gut is telling me very clearly that there is a lot of responsiveness to the fact that there is something wrong in this country."

Should he decide to make a White House bid, Sanders would not say if he would run as a Democrat or Independent.

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"You know the fact that I'm in Iowa, which is a caucus state, maybe speaks for itself, but I haven't made up my final decision," he said. "I've got to say - some of my strongest supporters say, 'Bernie, stay out of the damn Democratic Party. Run as an Independent.'"

Sanders is viewed as unabashedly progressive, often saying he wants to take on the billionaire class and that he supports doubling the minimum wage.

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When ABC News' David Wright compared Sanders' potential 2016 run to the vain effort of Don Quixote tilting at windmills, the senator said that was already on his mind.

"I don't want to tilt at windmills," he said. "I've got so much to do, but I just think that out there, there are so many people who are hurting, so many people who are disillusioned, so many people who are really viscerally upset that they're working longer hours for low wages and the billionaires are getting richer, and they need a voice."