"I think it's critically important that we stop trying to complicate healthcare and we start taking a look at what needs to be fixed in Obamacare," Sen. Heidi Heitkamp, D-North Dakota, told The Hill. "Until we actually have those conversations and we have bipartisan support, I think it's unrealistic to assume that we're going to see any kind of expansion of care."

The Hill talked to a handful of other centrist Senate Democrats — Florida's Bill Nelson, Delaware's Tom Carper, Indiana's Joe Donnelly and Virginia's Mark Warner — all of whom dodged questions about a public option.

Throughout most of her campaign for president, Clinton did not mention a public option. Her emphasis on health care was on expanding the ACA through its current framework, which relies mostly on expanding Medicaid access to more low-income people and subsidizing the coverage of private insurance coverage for individuals and families with moderate incomes.

However, caught off guard by a surprisingly strong challenge from the left during the primary from Sanders, Clinton proposed a number of bold progressive programs, including tuition-free college for most students and the public option.

America's Health Insurance Plans, the powerful trade group that represents for-profit insurers, is currently led by Marilyn Tavenner, the former head of the Centers of Medicare and Medicaid Services in the Obama administration. The group is bound to fiercely oppose any public option plan, which they argue would put private insurers out of business and ultimately lead to a single-payer system.