On the presidential campaign trail, Senator Bernie Sanders’ rallying cry is “political revolution.” The Vermont senator draws big crowds as he incriminates the wealthy for perpetuating an American oligarchy. Calling for policies that can transform a long-suffering lower-income majority into a true middle class, Sanders speaks passionately about the economic hardship of the 99 percent.

When I asked Sanders who his political hero is, he quickly named labor organizer Eugene V. Debs, the six-time socialist presidential candidate. His ideas, Sanders said, “ended up becoming part of Roosevelt’s New Deal.” Though he calls himself a socialist and sits in Congress as an independent, Sanders is running for president as a Democrat.

At the Iowa Democratic Party’s celebrated Jefferson-Jackson dinner, Sanders urged citizen activists not to “turn [their] backs on the political process.” He reiterated, “You are not on the sidelines of these struggles; you are in the middle, and that is what our campaign is about.”

This is Sanders’ effective message for his supporters outside the political orthodoxy: We need to operate within the Democratic Party in order to achieve a progressive agenda.

History demonstrates that alternative party candidates – including Theodore Roosevelt’s Bull Moose platform in 1912, Ross Perrot’s two independent bids in 1992 and 1996, and Ralph Nader’s green presidential campaigns — are destined to reinforce the status quo rather than upset it.

In choosing to run as a Democrat, Sanders has clearly learned a lesson from Henry Wallace’s unsuccessful 1948 third-party presidential campaign. Like the former Burlington, Vermont, mayor campaigning for a $15 living wage, Wallace endorsed a like-minded “people’s revolution” that makes genuine freedom attainable for working-class Americans....