The senators who have qualms about the health care bill and are threatening to work with the Republicans to prevent a vote should think of the consequences of refusing to allow your party a vote on its' most crucial issue. They would be saying that the damage to the country or to their political prospects is so much that they are willing to ruin the rest of their actual legislating career. This would harm their states because now the precedent had been set. A liberal democrat who disagreed with profoundly with something Nelson (nebraska), Lieberman(Conn.), Landreiu (La.) or Lincoln (Ark) really wanted for their state or the nation would be in a position to filibuster and do the same thing. Remember this is a case where the vast majority of your caucus is in support. This would undermine government if Democrats can't keep all sixty senators on procedural votes. If this was an issue like the Farm Bill, nuclear power, Gun rights, or even abortion rights which has significant bipartisan appeal it would be different. There are many pro gun Democrats, and pro choice Republicans. There are many Democrats against the Farm Bill subsidies because it is unfair to certain types of states or Republicans who are for the Farm bill because it helps certain types of states. That would stir up the pot so much that neither side is really implicated. It would be politics. But health care has been detemined to be the President's top agenda item, and well over 90 percent of Democrats have specifically campaigned to work on health care reform. In short, this is a Democratic issue. It would be similar to tax cuts for the Republicans.
Can you imagine if a Republican conference couldn't get the 60 votes to cut off debate on a tax cut? President Bush had this same type of debate early on in his Presidency. He wound up making a deal to make the tax cuts "temporary", thinking Republicans would never let them expire in such a short time period. It turns out he didn't realize how fragile his political coalition was. At least some of them will be reversed because there are 60 in the Democratic caucus. But... The major point is Bush won his major campaign policy item.
The Democrats who are thinking of denying votes should think hard if they want to end their legislative career because there will be some one there to object to their political wishes and block their advancement at every step. How would that help their state?
If you are a Lieberman or a Ben Nelson, and you are a national security conservative, you're going to need liberals for war funding and other tough votes to at least allow the vote so that the minority of Demorats and a majority of Republicans can support some of Obama's plans that appeal to the middle. Would you want the same standard applied then? If the liberals really think what you are doing is wrong, refuse to allow a vote and talk it to death?
Everything is not so simple. But this one is. If over fifty votes in your caucus want to do something, and no one in the other party will help, you either have to join the other party or help your party out.
The one exception would be if this is that one, two, or few issues where you are willing to stay and fight in your party; and end your political influence. Then you would have to think am I going to win this battle today, tomorrow, six weeks from now? Is some one going to cut a deal and leave me out of it, so that I lose both ways. After I retire, is the next person going to simply do what I refused to? That is complicated.
On health care, vote to allow debate, then vote to end debate, and then vote whatever you want on the bill.