The national limit on late-term abortion passed by the House of Representatives in June is a losing issue for pro-life Republicans, according to the  conventional  wisdom  in  the  press and the  Republican donor class. But there are two compelling reasons why the conventional wisdom is wrong.

First, nationwide polls indicate Americans support a ban on late-term abortions. A  Huffington Post/YouGov poll found that by a 2-to-1 margin (59 percent to 30 percent) Americans support banning almost all abortions after the twentieth week of gestation. "One of the clearest messages from Gallup trends is that  Americans oppose late-term abortion," according to a report by the polling firm in May. A  National Journalpoll found a smaller  majority of women and independents support the House bill. The measure garnered "plurality support across all income levels and [it] even fared well in the suburbs."

Second, the ten most competitive 2014 Senate races are almost all in red states that are more conservative than the country as a whole. Of these ten seats, two are held by Republicans (Kentucky and Georgia), four are held by retiring Democrats (West Virginia, South Dakota, Iowa, and Montana), and four are held by Democrats seeking reelection (Louisiana, Arkansas, Alaska, and North Carolina). Backing late-term abortion could prove toxic for some of these red state Democrats.

While walking between meetings and votes this past week in the Capitol, the four red state Democratic senators seeking reelection in 2014 commented on the proposed national late-term abortion limit for the first time to THE WEEKLY STANDARD. Both Kay Hagan of North Carolina and Mark Begich of Alaska said they would vote against the House bill if it comes up for a vote in the Senate.

"I always wait to see legislation, to see exactly what it says, but I would oppose that," Hagan told me. "Yes," Begich replied when asked if he'd vote against the bill banning late-term abortions, except in the cases of rape, incest, or when a health problem endangers the mother's life. "I'm pro-choice."

But Mark Pryor of Arkansas and Mary Landrieu of Louisiana, two senators who voted for the 2003 partial-birth abortion ban, said they didn't know how they would vote. "I'll have to look at it. I haven't focused on it," Pryor told me.

"I'm going to look at it. I've voted to end late-term abortions, " Landrieu said, referring to her vote for the partial-birth abortion ban.

"I do support, you know, the current constitutional outline which provides for decisions to be made which are very private in, you know, the early stages of pregnancy," Landrieu continued. "So I'm going to have to look at that bill and make a decision. I've opposed late-term abortion, but 20 weeks is mid-term."

"I've taken a lot of tough votes. That's what I'm here for," Landrieu said. She repeated again that she's opposed late-term abortion in the past, but "this isn't late-term, this is mid-term."

Self-identified pro-life Democratic senators Bob Casey of Pennsylvania and Joe Donnelly of Indiana didn't say how they'd vote. North Dakota senator Heidi Heitkamp said during the 2012 campaign that she believes "late term abortions should be illegal except when necessary to save the life of the mother," but she too declined to take a position on the House bill.

Senate Democratic leaders have sent  conflicting  messages about whether or not they will allow a vote on a late-term abortion bill, and a Senate companion to the House bill hasn't been introduced yet. But if it does come up for a vote, it will force senators like Pryor and Landrieu to make a tough choice: Vote "yes" and anger the most powerful Democratic interest group or vote "no" and put themselves at odds with a clear majority of voters.

"You can't get much more radical than opposing legislation that would protect women and babies from brutal late-term abortion beyond the fifth month of pregnancy," said Marjorie Dannenfelser, president of the pro-life Susan B. Anthony List. "Not only is opposing this common ground measure a moral mistake, it is a political one as well, especially for vulnerable senators in solid pro-life states."

"That Senators like Mary Landrieu would even hesitate to affirm this modest legislation shows just how beholden to the abortion industry many in the Senate have become," added Dannenfelser, whose organization spent $11 million on the 2010 mid-term elections. "As the 2014 elections approach, we will be working to ensure that constituents understand just how outside the mainstream these four senators have become."

If Landrieu decides to vote against the bill, she will have a very hard time arguing that abortions performed later than 20 weeks after conception are "not late-term." At that point in pregnancy, a baby is developed enough to feel pain and some can  survive long-term outside the womb.

"I'm here because it's easy for me to imagine these babies at 20 to 24 weeks post-fertilization age because they are my patients in the [neonatal intensive care unit],"  Dr. Colleen Malloy of Northwestern's Feinberg School of Medicine testified before Congress in 2012. "You can see the detail in the face," she said, showing a picture of an ultrasound. "You can see the movements--the 4D ultrasound images that we have now are real time images of babies kicking, moving, sucking their thumb--doing all the things babies do."

Contrary to Landrieu's assertion, the partial-birth abortion ban didn't actually ban abortions based on the gestational age of the baby, but rather its location. It banned a particular procedure used during the second- and third-trimester abortions in which the baby is first delivered breach past the navel before her skull is crushed by the abortionist. New York senator Daniel Patrick Moynihan called it "too close to infanticide." The bill passed in 2003 with the support of 16 Democratic senators, including Joe Biden and Harry Reid, and was signed in to law by President Bush. But the law ban  did not prohibit other late-term abortion procedures, such as dismemberment and lethal injection abortions.

In the wake of trial of Philadelphia doctor Kermit Gosnell, pro-lifers and a significant number of pro-choice  writers have argued that there isn't really a significant difference between killing a 23-week-old baby outside the womb, for which Gosnell was convicted of murder, and killing her inside the womb, which is perfectly legal in most states.

Some of the most prominent defenders of abortion rights, including Planned Parenthood president  Cecile Richards and House Democratic leader  Nancy Pelosi, have been unable to explain why the actions of Dr. Kermit Gosnell constituted murder but killing the same babies moments before birth should be perfectly legal.

When asked about the difference between infanticide and late-term abortion, Richards pointed to cases in which the baby is suffering from severe disabilities, effectively making an argument for fetal euthanasia. But when asked about late-term abortions on healthy babies, she walked away without even trying to make an argument.

And we do know that there are likley thousands, if not tens of thousands, elective late-term abortions perforemd every year in the United States. "Diana Greene Foster, associate professor of obstetrics and gynecology and the University of California, San Francisco, co-authored a forthcoming paper looking at more than  200 women who had abortions after 20 weeks for nonmedical reasons," wrote Michelle Goldberg in the  Daily Beast. "According to Foster, two thirds of them were delayed while they tried to raise money to pay for a termination. Twelve percent were teenagers, some of whom went months without realizing they were pregnant."

Foster looked at what happened to women who had wanted a late-term abortion but missed their clinic's self-imposed deadlines. "About 5 percent of the women, after they have had the baby, still wish they hadn’t. And the rest of them adjust," she  told the  New York Times.

The abortion issue was not a winning issue for Republicans in 2012 because Democrats, the press, and Republican gaffes focused attention on the issue of abortion in the case of rape, which Americans overwhelmingly think should be legal. But when the abortion debate is focused on taxpayer-funding of abortion under Obamacare, as it was in 2010, or partial-birth abortion, as it was in 2004, then that's a debate where the pro-life side is with the overwhelming majority of Americans.

"Even I have trouble explaining to my family that we are not about killing babies," Donna Brazile  said after the 2004 election. Abortion was an issue that "put us into the extreme and not the mainstream."

The extent to which the late-term abortion issue will hurt pro-choice Democrats in 2014 and beyond depends in part on whether or not Republican candidates will actually make an argument. In  1997, Gallup found that Americans backed a partial-birth abortion ban by a 15-point margin (55 percent to 40 percent). But in  2003, the margin of support had grown to 45 points (70 percent to 25 percent), and the bill became law. Debate can change opinions.

In the wake of the damaging comments on abortion in the case of rape made by Missouri and Indiana Senate candidates in 2012, Republican consultants and aides privately tell me that many Republican politicians are still spooked and don't want to talk about the issue at all. But the the lesson of the 2012 election and the Romney campaign should be precisely the opposite: It's hard to win an argument if you aren't willing to make an argument.