– Senators are back at work Monday, and their No. 1 priority remains trying to craft an alternative to ObamaCare. The problem is that Mitch McConnell's task of getting the necessary 50 votes seems to have gotten only more difficult over the holiday break, and that's raising a slew of stories about what happens if the GOP bill fails. Shoring up ObamaCare is one possibility, but another is the controversial idea of some kind of single-payer system. The long-shot concept, anathema to conservatives, is surfacing more and more in stories: Definition: Under a single-payer system, "doctors and hospitals are mostly private entities, but are paid exclusively by the government," explains a primer at Mother Jones. "Canada is single-payer, with each province acting as the sole source of payment to doctors and hospitals. In the US, Medicaid and traditional Medicare are single-payer." Tax hikes: Everybody would get core coverage regardless of income, job, or health status, explains Money, and people would no longer get insurance through their jobs. But paying for it would surely require new tax increases of some kind. Sanders, and others: The concept is gaining traction among Democrats, reports the Hill. Bernie Sanders promises to introduce a bill when debate ends on the GOP ObamaCare alternative. Sens. Elizabeth Warren and Kirsten Gillibrand back the concept, and in the House, a "Medicare for All" proposal by Rep. John Conyers has 113 co-sponsors. Warren, specifically, told the Wall Street Journal last month that "now it's time for the next step, and the next step is single payer." Please, no: Putting bureaucrats in charge of health care isn't the answer, writes Sally Pipes at Forbes. "Single-payer systems have endangered lives and reduced access to quality care everywhere they've been implemented," she notes, citing "deplorable care" in Britain and Canada and arguing that if Republicans needed any incentive to make progress on their health bill, the prospect of a single-payer system should do it. California: A bill to shift to a single-payer system stalled last month in the California Assembly, and the Los Angeles Times reports that a main reason is that it was "short on key policy specifics—most significantly, how to pay for it." Partisan divide: A Pew Research Center poll finds that 52% of Democrats support the single-payer idea, but the overall percentage in support drops to 33 when Republicans are added, reports CNN. For that reason, both sides seem to love talking about it, notes the story. Senate GOP plan: It's not dead yet, though the positions of conservatives and moderates within the GOP seem to have hardened in the last week, reports Politico. That makes McConnell's quest for a compromise acceptable to enough senators exceedingly difficult.