Harry Reid filled the amendment tree on health care reform, putting the Senate on the path to a series of cloture votes leading to final passage of the bill, without any further changes beyond the manager’s amendment. Barring some unforeseen circumstance, that’s the bill which will head into a conference committee with the House, with the goal of arriving at legislation that can pass both chambers on a final vote.

The conference report can be filibustered, and obviously the axis of Nelson and Lieberman, etc., will be watching any alterations to the bill closely and making known their objections. However, there are also substantial objections among coalitions in the House, many of which are in conflict with the compromises made in the Senate.

For context, remember that the House bill only passed by a bare 220-215 majority. The dropping of the public option may appeal to some Democrats who voted no, changing their vote, but that could be offset by those who are against other key provisions and would base their vote on it:

• Abortion: The compromise in the Senate with Ben Nelson doesn’t seem to have satisfied House members on either side of the divide. Bart Stupak was working to undermine the compromise before it was even announced, and members of the Pro-Choice Caucus sound unimpressed as well. Here’s the statement from Reps. Diana DeGette and Louise Slaughter on the Senate bill:

“As the Co-Chairs of the Congressional Pro-Choice Caucus, we have serious reservations about the abortion provision included in the U.S. Senate’s health care bill. This provision is not only offensive to people who believe in choice, but it is also possibly unconstitutional. As we have maintained throughout this process, health care reform should not be misused to take away access to health care. The more than 190-member Caucus will review this language carefully as we move forward on health care reform.”

“Possibly unconstitutional” is a strong statement. And virtually every choice group, from Planned Parenthood on down, has expressed strong opposition to the Nelson language. At issue are two things: the segregation of funds, where women who receive subsidies on the exchange would have to give two checks to their insurance company to get reproductive choice coverage, which just comes off as humiliating. And then there’s the state opt-out, where states could ban coverage in their state exchanges. That may be where the constitutional issues arise (although five states currently ban private coverage of abortion services).

The compromise could also force state-based rather than national exchanges, which would be significantly worse from a regulatory standpoint.

• Immigration: The manager’s amendment to the Senate bill did not change two provisions which would both ban undocumented immigrants from purchasing insurance coverage on the exchange, even with their own money, and which would delay legal immigrants from using the exchanges for five years. Luis Gutierrez of the Congressional Hispanic Caucus said a month ago that it would be “impossible” to vote for any measure that denies undocumented immigrants health care, and there are at least a handful of members of the CHC who may agree with him. The House bill did not include these restrictions, so Gutierrez and others have never been forced into a vote like this.

• The Public Option: Over 60 members of the Progressive Caucus signed multiple letters saying they would vote against any bill that didn’t include a public insurance option. They already compromised back on Medicare + 5% rates, but leaders of the Progressive Caucus like Raul Grijalva and Lynn Woolsey have indicated that they would find it difficult to compromise again. I wouldn’t guess that everyone who signed the letter agrees with them, but there may be another handful.

There are obviously other pieces of reform that House members may find distasteful and want to improve; in particular, the funding mechanism (excise tax on high-end insurance plans vs. surtax on millionaires) or the employer mandate (versus the “free-rider” measure in the Senate bill). Nobody has yet made an ultimatum on these measures, but labor is fighting these two particularly hard, so I wouldn’t be surprised to see some labor liberals in the House make that claim.

There are probably 25-30 House Democrats who, for whatever reason, won’t vote for any health care bill. That leaves a very small margin of error to lose Democrats on any of the above issues. And of course, if they are satisfied, they risk losing 1 or 2 Democrats on the razor-thin margins in the Senate, which would also sink the bill.

I wouldn’t etch final passage in stone just yet…