2020 Democratic presidential candidate Bernie Sanders is not letting his past failed run at the White House get him down.

Sanders, an independent senator from Vermont who caucuses with the Democrats, said in an interview on Sunday on NBC’s “Meet The Press” that instead of being disheartened by losing the 2016 Democratic primary to former Secretary of State Hillary Clinton, he feels encouraged by his successes since then.

“We took on the entire Democratic establishment, we took on the DNC, we took on every democratic governor, every democratic mayor. We transformed the party,” the self-described Democratic Socialist said. “Four years ago people are not talking about the issues we're talking about now.”

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Sanders’ fiery rhetoric and progressive ideology helped bring his more left-leaning colleagues into the political mainstream and are seen as the impetus for the success of other Democratic Socialist candidates like Rep. Alexandria Ocasio-Cortez of New York. The Vermont lawmaker's message appears to be resonating with a large portion of Democratic voters as a recent Fox News poll found that Sanders trailed only frontrunner, former Vice President Joe Biden – albeit by 18 points.

Sanders' campaign has unveiled a number of big proposals, including on Saturday when he announced he wants to suspend taxpayer funding of new charter schools and ban those that are for-profit as part of his plan to overhaul public education.

Saying charter schools are "exacerbating educational segregation," Sanders proposes more transparency and accountability for them, as well as limits on the pay of their chief executives. According to the campaign, the 10-point plan focuses on "reversing racial and economic segregation that is plaguing elementary and secondary schools."

To combat disparities in education funding, the senator from Vermont is proposing "large new investments in programs that serve high-poverty communities, support special needs students, and augment local efforts to integrate school districts." That also includes a minimum on per-pupil spending in all school districts across the country, as well as a universal school meal plan and a goal of closing "the gap in school infrastructure funding to renovate, modernize, and green the nation's schools."

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Earlier this year, Sanders proposed the Senate's "Medicare-for-all" bill, which is focused on single-payer as a way to "fully solve the health care crisis," an approach his team thinks adds to his progressive bona fides.

The Vermont senator's legislation would set up a four-year transition to government-run care for almost all health treatments, free of premiums or deductibles, with private insurance available as a supplement. Other 2020 Democrats – like Sens. Elizabeth Warren of Massachusetts, Kamala Harris of California, Corry Booker of New Jersey and Kirsten Gillibrand of New York -- have been less clear on how they would treat private insurers under a "Medicare-for-all" system, and each has supported more incremental steps to increase access to care.

The Associated Press contributed to this report.