The conventional wisdom on Senator Bernie Sanders of Vermont is that he’s a charming if impractical dreamer, a pie-in-the-sky socialist who’s good at inspiring young people and aging hippies, but hopeless at the knife fighting that real-life politics requires.

Despite the inherent limitations of a self-described democratic socialist who eschews the norms of Beltway fundraising, the Democratic presidential candidate from Vermont has won legislative victory after victory on an issue that has been dear to him since his days as Burlington’s mayor.

That issue is the simultaneously benign and revolutionary expansion of federally qualified community health clinics.

Over the years, Sanders has tucked away funding for health centers in appropriation bills signed by George W. Bush, into Barack Obama’s stimulus program, and through the earmarking process. But his biggest achievement came in 2010 through the Affordable Care Act. In a series of high-stakes legislative maneuvers, Sanders struck a deal to include $11 billion for health clinics in the law.

The result has made an indelible mark on American health care, extending the number of people served by clinics from 18 million before the ACA to an expected 28 million next year.

As one would expect, the program was largely met with plaudits from patients and public health experts, but it has also won praise from even the biggest Obamacare critics on Capitol Hill. In letters I obtained through multiple record requests, dozens of Republican lawmakers, including members of the House and Senate leadership, have privately praised the ACA clinic funding, calling health centers a vital provider in both rural and urban communities.

To Sanders, the clinics have served as an alternative to his preferred single-payer system. Community health centers accept anyone regardless of health, insurance status or ability to pay. They are founded and managed by a board composed of patients and local residents, so each center is customized to fit the needs of a community. No two health centers are alike.

In rural North Carolina, ACA-backed health centers now provide dental and nutrition services, while in San Francisco, the clinics provide translation services and outreach for immigrant families. In other areas, they provide mental health counseling, low-cost prescription drugs, and serve as the primary care doctors for entire counties. They have also served as a platform for innovation, introducing electronic medical record systems and paving the way with new methods for tracking those most susceptible for heart disease and diabetes.

Author John Dittmer, in The Good Doctors, traces the history of the modern health center to the civil rights activists who ventured into the South during the early 1960s. The activists were seen as outside agitators, and local doctors refused to treat them. As a solution, volunteer bands of physicians were organized by a group called the Medical Committee for Human Rights.

Beyond treating the civil rights workers, the MCHR physicians were struck by the stark disparity in health services, encountering many African-Americans who had never seen a doctor before in their lives. The activist physicians returned to the South after the “Freedom Rides” to found a small clinic in Mound Bayou, Mississippi, in the heart of the Mississippi Delta, and by doing so, began a movement to launch health clinics across the country in underserved areas. Winning support from President Lyndon Johnson’s Office of Economic Opportunity, the clinics became part of Johnson’s “War on Poverty.”

Over the years, health centers have gained support on a bipartisan basis. Health centers secured critical funding from the efforts of the late Sen. Ted Kennedy, D-Mass., and both George W. Bush and John McCain campaigned on pledges to expand them.

Sanders’s place in health clinic history will be remembered for his forceful role in the winter of the health reform debate. In December 2009, tensions ran high as Congress inched closer to a final health reform deal. Sen. Harry Reid, D-Nev., tapped Sanders to help win support from liberals who thought the bill was too weak as well as from Democrats from rural states who were facing mounting pressure. More funding for community health centers, Sanders argued, was a win-win solution for both camps, since the program would ensure access to health care for even the most remote areas of the country while also helping those without insurance. Sen. Ben Nelson, D-Neb., among others, held out to the very last moment.

Two days before the Senate voted to break a Republican filibuster of the bill, Reid called on Sanders to make his case on the Senate floor. Sanders, in typical fashion, said the legislation was far from perfect, but thundered about the common-sense need for health centers, citing the acute demand for more primary care doctors, the cost-savings from patients who would otherwise use the emergency room for the common cold, the patient-centered model of clinics, and so on. Senate Democrats rallied and overcame the Republican filibuster.