The Republican Party ought to distribute a list of rhetorical no-no's that office-holders and candidates should avoid at all costs. Topping the list should be the slavery analogy.

In recent months, Republicans have compared food stamps, Obamacare, gun control and the national debt to the South's "peculiar institution" of human bondage that flourished until 150 years ago. What those comparisons were supposed to signify, other than the cluelessness of the speaker, is unclear.

Still, every once in a while the slavery analogy seems to hit home. Consider the state of the state address delivered Wednesday by Kansas Gov. Sam Brownback.

Brownback flattered his ultraconservative followers by equating Kansas' gun- and bible-toting abolitionists from the 1850s with the extremist anti-abortion protesters that staged widespread protests in the state in 1991.

"The chains of bondage of our brothers rubbed our skin and our hearts raw until we could stand it no more and erupted into 'Bleeding Kansas,' " Brownback intoned, invoking the deadly skirmishes between Free-Staters and pro-slavery Border Ruffians that prefigured the U.S. Civil War. He then continued, referring to the abortion protests of 1991, "The Summer of Mercy sprung forth in Kansas as we could no longer tolerate the death of innocent children."

The so-called Summer of Mercy protests brought thousands of abortion protesters to Wichita, and are credited with launching the most desperate and ultimately violent actions within the anti-abortion movement. The most prominent target was George Tiller, the late-term abortion doctor who was murdered in 2009.

The exhaustively detailed book "Wrath of Angels," by Kansas City Star reporter Judy Thomas and James Risen of The New York Times, details the Summer of Mercy and the role of the group Operation Rescue in organizing the protests.

The protests lasted 46 days. The goal was to shut down Tiller's clinic. Federal marshals were necessary to keep order, along with a judge's ruling. There were nearly 2,700 arrests. But rather than ushering in a new protest culture that would touch the conscience of the nation, the Summer of Mercy ended in desperation for the anti-abortion movement, and gave birth to its most heinous and ultimately violence-ridden factions.

Far from accomplishing its goal, Thomas and Risen wrote, the episode "would serve as a warning of the movement's coming slide into extremism and violence."

It's hardly something to praise, no matter what your opinion of abortion. But that's why Brownback tried to draw a moral parallel with Bleeding Kansas. After all, John Brown, the legendary antislavery militant, is immortalized in a prominent mural at the Kansas State Capitol — and he had led (before his raid at Harpers Ferry) a murderous foray that butchered five men at Pottawatomie Creek.

We give Brown a pass — he's an American hero — and so we must give the bombers and shooters of the pro-life movement a pass, too. Hey, they're fighting for the lives of the unborn, which is the same as fighting for the freedom of a race of people enslaved for the benefit of another race.

Is it the same thing? I'm not convinced it is — and I personally believe that abortion is wrong. A fetus is human life that deserves to be protected. How that is best accomplished is where I differ from many of those who stormed Wichita that summer. Prevent unwanted pregnancies in the first place, instead of harassing women and rising to a level of violence against the doctors who try to help them.

Slavery was a brutal economic system. People were captured into it. They were born and bred into it.

It was codified by law for the benefit of a certain class of white people but it also nourished a prospering nation. Many of the economic gains of the fledgling United States can be credited to the free labor of slavery. That's why its legacy is so firmly entrenched, why the forces that benefited from it fought on well into the 20th century to maintain African American peonage, agitating against civil rights laws and other government efforts to establish equality.

Abortion, whether you consider it permissible or not, is a personal dilemma, pitting the rights and welfare of a woman against the rights of the fetus she is carrying. Conception after rape or incest, pregnancies that risk the mother's life, and extreme malformations of a fetus are some of the circumstances that can seriously complicate this dilemma.

The abortion question is not the slavery question. If abortion is evil, it is not a social evil, a crime against a class of people for the benefit of another. The zealots that Brownback praised — and upon whom he no doubt depends in his upcoming election — are not doing their cause or the victims it claims to protect any good by pretending that this weak analogy holds.

Mary Sanchez is a syndicated writer from Kansas. Her email is msanchez@kcstar.com.