"Trojan horse" you mean. A "poison pill" is when you attach something to a bill which makes it very hard for other people to vote for it. The Save Springfield bill with a Perverted Arts amendment.
The GOP has (and had when it was in power) the ability to shape health reform. They could have tried to create a sustainable system which would still be mostly market-based and preclude the need for single payer in the future. Even now, if they could deliver even 10 votes in the Senate for the bill, they'd instantly get a bunch of concessions.
But they've decided to do their best to stop a bill from passing no matter what's in it. If it works, like it did in '93, then they can say Obama's a failure who can't get anything done. If it doesn't, then massively important legislation is going to be passed without their being able to influence it.
GS: If you want to learn more about the details of the bill, read
this, Ezra Klein's blog at the Washington Post, Jonathan Cohn's blog at The New Republic, and the Health archive at the Center for Budget and Policy Priorities.