Republican leadership has a not so-subtle-hint for Todd Akin: They would like the Missouri Senate candidate, who remarked that "legitimate rape" rarely results in pregnancy, out of the race — and sooner rather than later. The National Republican Senatorial Committee has pulled $5 million in ads and multiple senators have demanded he step down.

"Congressman Akin's statements were wrong, offensive, and indefensible,"NRSC chair Sen. John Cornyn (R-Tex.) said, offering a not-so-subtle suggestion that Akin step aside. "Over the next 24 hours, Congressman Akin should carefully consider what is best for him,"

Sen. Ron Johnson (R-Wis.) was more to the point in a Monday morning tweet: "Todd Akin’s statements are reprehensible and inexcusable. He should step aside today for the good of the nation."

Pro-life groups, however, have taken a decidedly different take. Both the Susan B. Anthony List and Family Research Council have stood by Akin. They don't see him as a politician who has made a career ending gaffe. In their view, he's a strong abortion right opponent who articulated a tenet of the pro-life movement: Abortion should be illegal in all situations, rape included.

"Todd Akin ... has a record of voting to protect human life," said Susan B. Anthony List President Marjorie Dannenfelser, reaffirming her support in a statement. He "has been an excellent partner in the fight for the unborn."

Akin's remarks — and the ensuing reactions — underscore a major tension between pro-life principles and politics. The anti-abortion movement rests on a moral objection to all abortions, no matter the situation. It must exist, however, within a political reality that is hostile to flat-out abortion bans, the kind of law that Akin supports.

Exceptions to abortion restrictions, which carve out different rules for rape victims, force the politics and principles into a head-on collision. While about half of American voters identify as pro-life, a full 75 percent thought abortion should be legal in cases of rape or incest, according to a Gallup poll in 2011. Only 20 percent of Americans believe abortion should be illegal in all situations.

"The basic pro-life world view, within the movement, is that abortion is wrong because it is the killing of an innocent human being," says sociologist Ziad Munson, author of "The Making of Pro-Life Activists." "If one takes that position, then it doesn't matter the way in which the development of that life might endanger other people."

For his book, Munson spent hours interviewing 82 rank-and-file pro-life activists in four American cities. He heard this argument — that abortion is wrong, no matter what the circumstances — again and again. Sandra, a 34-year-old activist from, Oklahoma City, explained to him why she would not support abortion in the case of a 10-year-old girl who was raped.

"Every person is a person in their own person in their own right, in their own merit, and if a life is conceived it was meant to be conceived, because it has a reason and a purpose on this Earth," she told him.

A 68-year-old activist from Twin Cities put it another way: “Killing something is wrong. It’s not killing a rabbit or a bird, it’s a fellow human being. What do people think it is? A baby is a human being.”

Patrick Johnston, a family physician in Ohio who directs the Association of Pro-Life Physicians, shares that worldview. He opposes rape exceptions in abortion laws and currently collecting signatures for a ballot initiative that would ban all abortion in his state.

"When you make exceptions you lose the ability to be persuasive," Johnston said in an interview. "You show you don't believe in your own teaching, that life begins at conception. You show you're a hypocrite and lose the ability to make a moral case when you resort to pragmatism."

The Republican party platform endorses this philosophy, too. It is set to endorse a "human life amendment" at its conference in Tampa next week, which would apply the 14th Amendments "protections ... to unborn children." This is not new: The party supported similar language in 2004 and 2008.

Opposition to rape exceptions is not unusual among the party's most prominent members. Former Pennsylvania senator Rick Santorum endorsed banning abortion without exception during his run for president as did Texas Gov. Rick Perry.

Rep. Paul Ryan has backed this position by co-sponsoring the Sanctity of Life Act, a bill that would outlaw abortion altogether by declaring life to begin at conception.

Two-hundred-and-twenty-seven endorsed the No Tax Payer Funding for Abortion Act, which would only carve out an exception for "forcible rape." That could significantly narrow exemptions for rape victims by presumably excluding certain cases like statutory rape, where one party may not have experienced force but was also too young to consent.

The moral underpinnings of pro-life activists can, however, run up against hard political realities. The vast majority of Americans do support legal abortion in the case of rape or incest. Gallup polls have reliably found that three-quarters of Americans support a woman's right to terminate a pregnancy in that situation, even more than they support abortion in cases where a woman's mental health may be endangered or there's evidence the fetus may be physically or mentally impaired.

That explains why laws that attempt to shrink exceptions for these cases, such as the No Tax Payer Funding for Abortion Act, often get met with public outcry. The language there ultimately had to be revised to include a more expansive rape exception that mirrors what tends to show up in most other abortion restrictions.

Attempts to pass all-out abortion bans have routinely failed at ballot box, too. A Mississippi law, which would have banned abortion by declaring life to begin at conception, was rejected by 55 percent of the voters. Attempts in Colorado to pass a similar law have failed by double-digit margins.

That's left the pro-life movement choosing between the lesser of two evils: Supporting abortion bans that do not have a shot at becoming law, or standing behind imperfect restrictions with fewer political liabilities.

"It's only a matter of political expediency that they're willing to give ground," Munson says of many pro-life legislators. "They understand that [their position] is not the position of the vast majority of Americans. That doesn't change their fundamental beliefs that there shouldn't be a rape exception."