Presidential candidate and U.S. Senator Elizabeth Warren (D-MA) speaks at a campaign rally at Keene State College in Keene, New Hampshire, September 25, 2019. Brian Snyder | Reuters

Sen. Elizabeth Warren pledged Friday not to raise middle-class taxes to fund her "Medicare for All" plan, responding to pressure she faced as she emerged as a front-runner in the race for the 2020 Democratic presidential nomination. In a new outline, Warren's campaign said her single-payer health plan would cost the country "just under" $52 trillion over a decade, which includes $20.5 trillion in new federal spending. It estimates the proposal would cost just less than the estimated $52 trillion in spending for the current system over 10 years.

The Massachusetts Democrat's campaign said her plan would give every American "full health coverage, and coverage for long-term care." It added that it would do so with "not one penny in middle-class tax increases" — a response to criticism from rivals such as South Bend, Indiana, Mayor Pete Buttigieg. As she saw her support swell in national and early-state polls in recent weeks, Warren faced more pressure to explain about how she would fund a single-payer, government-run insurance system. While she had not answered specifically whether her plan would hike taxes on middle-class Americans, she repeatedly said it would cut costs by reducing spending on health care. Warren's plan meets the demand for a sprawling system to cover all Americans amid widening complaints about what many consider an unfair and expensive U.S. health system. The seismic changes Warren seeks — from the elimination of private health care to tax hikes on corporations and the wealthy and even changes to military spending — will likely have a tough time passing the Senate, even if Democrats win a narrow majority in the chamber next year. It would even face dim prospects in the Democratic-held House. On Friday, House Speaker Nancy Pelosi told Bloomberg News that she is "not a big fan of Medicare for All."