For a few weeks there, Sen. Ben Nelson looked like a pro-life hero. The Nebraska Democrat was engaged in a standoff with leaders of his party over  a Senate health care bill that failed to protect taxpayers from subsidizing abortion. He boldly declared his opposition to any bill that did not contain language consonant with the amendment to the House bill sponsored by Rep. Bart Stupak, D-Mich., that upheld the longstanding principle in federal law that stipulates no public funding for abortions or insurance policies that provide abortion coverage.

"Taxpayers shouldn't be required to pay for other people's abortions," Nelson declared. "It's just that simple."

But nothing is ever simple in Washington. Last weekend, after 13 hours of back-room bargaining, a phone call from Air Force One and a promise that the federal government will pay all of the costs for new Medicaid enrollees in Nebraska indefinitely -- a perk worth $100 million over 10 years that no other state enjoys -- Nelson the principled statesman devolved into Nelson the pork-barrel politician. He capitulated on the abortion issue, agreeing to a "compromise" that amounts to little more than an accounting gimmick.

The difference between Nelson's agreed-upon language in the Senate bill and the House bill language that he originally endorsed is significant. Under the House bill, consumers who use federal subsidies to purchase health care coverage through a proposed health insurance exchange would not be allowed to purchase plans that pay for elective abortions. Those consumers would need to use their own money to purchase separate abortion riders.

In the Senate bill, consumers using federal subsidies could purchase plans with abortion coverage. The only caveat: They must write two separate premium checks -- one for abortion coverage and one for the rest of the coverage.

Nelson has tried to save face with pro-life constituents by noting that individual states can pass laws banning abortion coverage in the insurance exchange. But that concession already was in place before his negotiations, and taxpayers in those "opt-out" states still may be forced to finance abortions elsewhere.

To their credit, many of Nelson's Nebraska constituents are unimpressed by the financial sweeteners that he won in exchange for his retreat on abortion. Nor has the senator endeared himself to the majority of Americans whom a recent Gallup Poll found identifying as "pro-life" rather than "pro-choice." According to a Quinnipiac University survey released Tuesday, 72 percent of voters oppose using any public money in the health care overhaul to pay for abortions, and 53 percent "mostly disapprove" of the health care plan. Those numbers spell trouble for Democrats seeking re-election in 2010 and for those -- like pro-choice Missouri Sen. Claire McCaskill -- who pledged to support the status quo when it came to bans on federal funding of abortion.

Reversals such as McCaskill's and Nelson's are not surprising. Pro-life voters are accustomed to broken promises from self-described centrists and opportunistic politicians who jettison their abortion opposition for a bigger slice of the Beltway pie. With powerful, well-heeled interests arrayed against their cause, pro-lifers must rely on conviction politicians to advance their cause. And conviction politicians are rare.

The good news: Slowly but perceptibly, and despite the powers-that-be in Washington, public opinion is swinging in the pro-life direction. More Americans are realizing that there is little difference between the baby whose ultrasound image graces our refrigerator door and the one whose tiny body lies dismembered and abandoned in a dumpster outside an abortion clinic. We are beginning to question the perverse logic of laws that ascribe personhood only to those human beings whom we declare wanted, while designating others as disposable.

Tonight, millions of Americans celebrate the coming of a child conceived by an unwed mother, born into poverty, and regarded as a nuisance by the authorities of his day. It's as good a time as any to remind ourselves and our lawmakers that human life in every stage deserves protection, and any law that purports to advance social justice must begin by upholding that self-evident truth.

Colleen Carroll Campbell is an author, television and radio host and St. Louis-based fellow at the Ethics and Public Policy Center. Her website is www.colleen-campbell.com.