“May we mourn what abortion reveals about the conscience of our nation,” she said, her voice quivering as she noted that none of her colleagues had acknowledged that half of those aborted are female. “We go to extraordinary lengths to save not only human beings but even animals because we value life so much. However, there are many who do not hold the unborn in the same esteem.”

Even if Democrats believed the political upper hand was theirs as they used the issue of reproductive rights to portray their opponents yet again as hostile and indifferent to the needs of women, it was clear that the question at hand — the termination of pregnancies that are five months or more along — was an uncomfortable one.

At a news conference Tuesday morning led by Democrats who favor abortion rights, the mood quickly turned tense after two journalists tried to press the representatives about their support for late-term abortions. Representative Diana DeGette of Colorado cut off questions after being asked whether she would draw the line at legal abortion later in pregnancy. “The Supreme Court has spoken, and this bill is unconstitutional. Next question,” she said.

The debate was marked by graphic descriptions of abortion procedures and medical claims. Representative Michael C. Burgess, a Texas Republican who practiced as an obstetrician before joining Congress, appeared to suggest that male fetuses are capable of fondling themselves.

“They have movements that are purposeful,” Mr. Burgess said during a debate of the bill during the House Rules Committee meeting on Monday. “They stroke their face. If they’re a male baby, they may have their hand between their legs. I mean, they feel pleasure, why is it so hard to think that they could feel pain?”

Democrats used the debate to mock Republicans’ claims that their focus was on the economy and job growth. They repeatedly interrupted the floor proceedings to make rhetorical jabs that were masked as parliamentary inquiries, like asking when the House was scheduled to take up the student loan interest rate bill or why a Republican member of the Judiciary Committee was not managing debate on the bill, which is customary.