Former President Bill Clinton is due to visit Capitol Hill today to talk healthcare reform with Senate Democrats and their independent allies.

The meeting’s important because Democrats have yet to find the 60 votes they need to stop Senate Republicans from blocking President Barack Obama’s signature domestic issue. House Democrats got their end of the job done over the weekend by passing landmark legislation.

Clinton’s presidency was overshadowed by his own failed bid to reform the healthcare system in the 1990s. But NBC said he could help sway Democrats wavering in the current debate, including Sen. Blanche Lincoln of his home state, Arkansas. 

A big obstacle that Clinton, Obama and Senate Democrats face seems as old as human nature: people who will cooperate — if they get their own way.

This time, a small clutch of moderates want their own way on the so-called public option, a proposal to offer government supported low-cost health coverage that is anathema to Republicans and the insurance industry.

Some senators are categorical about what they want.

For independent Sen. Joe Lieberman of Connecticut — a state long associated with insurance interests — opposition to the public option is a moral issue. “If the public option plan is in there, as a matter of conscience, I will not allow this bill to come to a final vote,” he said at the weekend on Fox News.

But his independent neighbor to the north, Sen. Bernie Sanders of Vermont, sounds like Lieberman’s polar opposite: “It would be outrageous to me, that when you have an overwhelming majority of Americans wanting a strong public option, that we do not deliver that.”

Others are not so categorical — until you get to the nitty gritty.

Sen. Ben Nelson of Nebraska told NBC he could back a public option, but not if states have to make the effort to opt out. Why? Because he doesn’t want them in the system unless they want to be there.

“I don’t think there is anything to be gained by opting out,” Nelson said. “I would look at the ability of the states to opt in, so that the states could make the decisions themselves.”

It seems a small distinction but may prove important. Reform advocates fear their adversaries could easily defeat healthcare reform at the state level, where small numbers of health insurers can sometimes hold a near monopoly.

Obama hopes to sign a healthcare reform bill by the end of the year.

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Photo Credits: Reuters/Chip East (Clinton); Reuters/Jonathan Ernst (Lincoln); Reuters/Mike Segar (Lieberman); Reuters/Chris Helgren (Sanders); Reuters/Jonathan Ernst (Nelson)