It's the latest controversy to hit the health care overhaul in a week that has seen Republicans sharpen their attacks and some Democrats start to waver on President Barack Obama's top domestic priority.
Abortion is not mentioned in the 1,018-page bill that Democratic leaders hope will be approved by the last of three House committees this week. Supporters of the legislation say that means the bill is neutral.
But abortion opponents say the bill's silence is precisely the problem.
Without an explicit prohibition on federal funding for abortion, it could be included in taxpayer-subsidized coverage offered through the health overhaul plan, abortion opponents say.
"We cannot support any health care reform proposal unless it explicitly excludes abortion from the scope of any government-defined or subsidized health insurance plan," a group of 20 Democratic representatives said in a June 25 letter to House Speaker Nancy Pelosi, D-Calif.
When the legislation was unveiled last week, it failed to include language abortion opponents were seeking. Now they are going public. Rep. Bart Stupak, D-Mich., who helped draft the letter to Pelosi, plans to join lawmakers of both parties Wednesday at a news conference to criticize the legislation.
The Supreme Court has established a woman's right to abortion, but federal law prohibits government funds from being used to pay for the procedure in most cases. However, nearly 90 percent of employer-based private insurance plans routinely cover abortion.
The Democratic health overhaul plan envisions setting up a new health insurance marketplace — called an exchange — through which individuals and businesses could get coverage similar to what's now available for employees of large companies. Government subsidies would be available for individuals and families making up to four times the federal poverty level. Abortion rights supporters say prohibiting plans in the exchange from covering the procedure amounts to taking away a right that women now have.
House Energy and Commerce Committee Chairman Henry Waxman, D-Calif., is trying to find a compromise, but that may not be easy. Not only do abortion opponents want to block funding, they also want to make sure that the procedure is not included in the benefits package.
Separately, another group of lawmakers wrote Pelosi on Tuesday urging a compromise that would leave the decision on abortion coverage up to insurers doing business in the exchange, but forbid the carriers from using any dollars from federal subsidies to pay for ending pregnancies.
"This solution maintains the current status quo in the private market — where insurance companies can choose whether to include this coverage in their plans and individuals can choose which plan (and what sort of coverage) fits their individual needs and values, while ensuring that no federal funds are used to pay for abortions," said the letter from Rep. Tim Ryan, D-Ohio, and three other Democrats.
However, it's unclear whether insurance companies could keep federal subsidies separate from other funds they receive from individuals and employers to cover premiums.
In the Senate, Finance Committee Chairman Max Baucus vowed that he would not let abortion controversies "embroil" the health care overhaul.
"Health care reform is not about that issue at all," Baucus, D-Mont., said Tuesday. He said the Senate plan would be "neutral — status quo."
Obama, who supports abortion rights, sidestepped a question on the brewing controversy. "Rather than wade into that issue at this point, I think that it's appropriate for us to figure out how to just deliver on the cost savings and not get distracted by the abortion debate," the president said in an interview with CBS News.