Lawmakers worked into the night setting the rule that lays out the framework for today's debate.
A sticking point was abortion and whether lawmakers will be allowed to vote on an amendment offered by pro-life Democrats.
The Rules Committee will allow a vote on that amendment, supported by the religious and pro-life groups, and with Republican support it's likely to pass. (For more on that, read this.)
Here's about how the day will work. This morning Democrats and Republicans will start by debating the rule they wrote late last night. (To really get technical, read the rule here.)
Many of the arguments for and against the rule will be the same as those for and against the health care plan, but the rule debate is only step one.
In nearly all cases, it will be a party-line vote to approve the rule.
Once that's done, general debate on the 1,900-page bill will last about four hours. Next up will be the abortion amendment, and then Republicans will have an hour to present and debate their substitute bill. (For more on that, read this.)
After that, they will vote on the Republican option, some procedural details and, finally, the House Democrats' health care bill. If it passes, it will indeed be historic - the farthest health care reform has ever made it through Congress (though there will still be a long way to go before it's law).
There are Democrats who are will vote against the bill, several have already announced their opposition.
There's always a chance something will go wrong, votes will slip away or Republicans will succeed in efforts to kill the bill with parliamentary tactics. But sources tell TPMDC that sort of delay is unlikely.
In another sign they will make it happen today, Obama plans to make a statement in the White House Rose Garden at 2:30 before heading to Camp David for the night.