It only took polls saying that:
... 72 percent of those questioned supported a government-administered insurance plan — something like Medicare for those under 65 — that would compete for customers with private insurers. Twenty percent said they were opposed ... with half of those who call themselves Republicans saying they would support a public plan, along with nearly three-fourths of independents and almost nine in 10 Democrats.
... to "embolden" Democrats to maybe stand firm on health care reform:
Emboldened by polls that show public backing for a government health insurance plan, Democrats are moving to make it a politically defining issue in the debate over the future of medical care.
Behind-the-scenes attempts to get a deal with Republicans on nonprofit co-ops as an alternative to a public plan have led only to frustration, complains a key Democrat. He and his colleagues may have to go it alone, said Sen. Chuck Schumer.
I will try not to roll my eyes at the idea of calling a nineteen (or twenty) seat majority and the backing of 72% of the public as "going it alone."