In a nutshell, the left thought healthcare would be “free”.
When it became obvious that they would have to pay for it, they started to oppose it.
Those who still support it are probably still ignorant of the requirement to pay for the insurance.
They initially lobbied for single-payer, but Obama took that off the table from the start for political reasons. So free #2 was the public plan. That would be free in the sense that taxpayers would be forced to support it, and premiums would be based on ‘ability to pay’ while everyone would get the same benefits.
But now the Senate-Reid bill has no public option. Just the mandate to buy insurance from evil greedy corporations they hate with some subsidies. The lib's hate this, call it Leiber-care after Leiberman, but many just cant bring themselves blame O for some reason.