WASHINGTON -- Kamala Harris released a health care proposal Monday seeking to bridge the Democratic Party's disparate factions. Instead, she drew criticism from virtually everyone.

Progressives took issue with the presidential candidate for stopping short of the full-scale health care overhaul embodied by the "Medicare for All" legislation. Her more moderate rivals, meanwhile, said she was trying to have it all without taking a firm position on one of the most animating issues in the primary.

The onslaught offered a preview of the Democrat-on-Democrat fighting likely to unfold over two nights of presidential debates that begin today. It left Harris back in the uncomfortable spot she's been for months: explaining herself on health care. Campaigning on Monday in Detroit, she praised Medicare for All's chief architect, Vermont Sen. Bernie Sanders, for "making sure this is a front and center topic" even as she distanced herself from his strategy.

"I have a vision of what it should be, and the existing plans that are being offered did not express what I wanted," the California senator told reporters.

Medicare for All has become a central focus in the Democratic primary, with the most progressive candidates calling for a revolutionary approach to providing government insurance coverage for all Americans at a lower price than the private market.

But Harris split from that approach. She envisions a role for private insurers as long as they follow the government's rules. She would slow the transition to 10 years from the four Sanders has proposed. And she has ruled out tax increases on middle-income Americans, an idea to which Sanders has expressed openness in exchange for lowering the price of health coverage.

Few rushed to align themselves with the Harris proposal.

A top adviser to Joe Biden, with whom Harris memorably clashed during the first debate, blasted the California senator's plan as a failed attempt to please all sides in the debate and warned her decision to push a 10-year transition obscures the full cost of her approach.

"This new, have-it-every-which-way approach pushes the extremely challenging implementation of the Medicare for All part of this plan ten years into the future, meaning it would not occur on the watch of even a two-term administration," said Biden's deputy campaign manager, Kate Bedingfield. "The result? A Bernie Sanders-lite Medicare for All and a refusal to be straight with the American middle class, who would have a large tax increase forced on them with this plan."

Harris also got hit from the left over her health care tightrope walk. Sanders campaign manager Faiz Shakir accused her of "continuing her gradual backdown from Medicare for All" and suggested she had been inconsistent on the issue of health care.

Adam Gaffney, the president of Physicians for a National Health Program, said Harris' plan has "several major shortcomings," including the continuation of private insurance and the longer transition period.

"This plan continues to give private insurance a very central role in the health care system," he said. "We have seen for decades that that does not work."

But Topher Spiro, vice president for health policy at the left-leaning think tank Center for American Progress, lauded Harris for trying to assuage "concerns that people have about disruption and about an abrupt transition" away from a largely employer-based health insurance system.

Spiro likened Harris' plan to the current design of Medicare and Medicaid, which he said "shows it's possible to have a government program that provides benefits through private options that is very cost-efficient." He declined to say whether he consulted with the campaign on its plan beyond providing information on Medicare Extra, his group's proposed alternative to Sanders' Medicare for All.