Republicans argue that the Senate health care bill would add an extra $1 trillion to the budget deficit even though the nonpartisan Congressional Budget Office has said it would reduce the deficit by $132 billion over 10 years -- a figure often touted by the president.
So what happens now? The Senate legislation will now have to be reconciled with the House bill, which passed in November. A conference committee from both chambers will attempt to merge the two bills, a process which is expected to go into February. The House returns on Jan. 12, the Senate Jan. 19, which leaves little time to get the bill to the president before his State of the Union address. Both chambers have to approve exactly the same bill, with a simple majority, before sending it to the president.
Democratic leaders have expressed confidence that they can clear this final hurdle, but they are likely to face a tough time resolving differences among members of their own caucus. Some liberal members of the House were upset by the Senate's removal of the public option plan to appease senators such as Nelson and independent Sen. Joe Lieberman of Connecticut.
"A conference report is unlikely to sufficiently bridge the gap between these two very different bills," Rep. Louise Slaughter, D-N.Y., chairwoman of the House Rules Committee, wrote in a blistering CNN.com column Wednesday. "It's time that we draw the line on this weak bill and ask the Senate to go back to the drawing board. The American people deserve at least that."
Even though both health care bills were crafted by Democrats and are similar in some ways, there are several significant differences between the two.
Some senators, such as Nelson, have warned that they could yank their support for the health care bill if changes are made. For some members of the Senate, the House version of the health care bill was dead on arrival and many say that members of the House will simply have to cave in.
Meanwhile, some House Democrats, such as Rep. Bart Stupak of Michigan, who wanted strict language prohibiting federal funding for abortion, say they are unhappy with the language in the Senate bill and other concessions given to senators. Stupak called the bill unacceptable but added, "I remain optimistic that we can work this out."
Deputy White House press secretary Bill Burton also expressed optimism, telling reporters today the House and Senate versions were "95 percent similar."
"We're going to be actively working to iron out the rest of the differences and get a bill passed and signed," Burton said.
Here are some key differences between the House and Senate bills:
The Senate bill curbs costs by taxing so-called "Cadillac plans," high-deductible insurance plans that some believe are one of the reasons for high insurance costs. The plan would impose a 40 percent tax on insurance coverage in which premiums are more than $8,500 for an individual and $23,000 for a family.
The plan drew fire from the union groups, many employees of which often negotiate lower salaries in exchange for better health care coverage. Some House Democrats are also opposing it for that reason.
In an interview with NPR Wednesday, Obama said this tax would be a good idea.