Rep. Alexandria Ocasio-Cortez (D-N.Y.) conceded Thursday that Sen. Bernie Sanders' signature Medicare for All proposal would face congressional roadblocks if he was elected president, telling HuffPost: “A president can’t wave a magic wand and pass any legislation they want."

Why it matters: Ocasio-Cortez is a vocal proponent of Medicare for All and one of Sanders' highest-profile surrogates. She told HuffPost: "The worst-case scenario? We compromise deeply and we end up getting a public option. Is that a nightmare? I don’t think so."

More moderate 2020 candidates like Pete Buttigieg have faced criticism from the left on their health care proposals, despite endorsing a public option. Buttigieg has framed his "Medicare for All Who Want It" as a more practical pathway to Medicare for All.

Ocasio-Cortez argued that even if Medicare for All is unrealistic in Sanders' first term, having an ambitious progressive platform is still important to help push the party further left.

Where it stands: Out of the 2020 Democratic candidates, only Sanders and Elizabeth Warren support Medicare for All.

All other 2020 Democrats support plans that allow Americans to keep private insurance unless they want to choose coverage from a public plan.

plans that allow Americans to keep private insurance unless they want to choose coverage from a public plan. The health care industry, particularly hospitals, opposes a public option almost as fiercely as it opposes single-payer — and would fight it in Congress with just as much help from Republicans, according to Axios' Sam Baker.

Go deeper: Democrats like both Medicare for All and a public option