I am personally opposed to slavery, but...

Pro-Life apologist Scott Klusendorf says:

"Abortion intentionally kills a million innocent human beings every year. Given that brutal reality, pro-lifers are right to put greater emphasis on the lives of the unborn than the paychecks of the born. Demanding they do more is like telling an abolitionist in 1860, 'You can’t be against slavery unless you address its underlying causes.'

Slavery is wrong. Abortion is wrong. Neither statement requires further qualification.

What an apt analogy.  How about:

"I believe that slavery should be safe, legal, and rare."

"I am personally opposed to slavery, but I don't believe that I can impose my beliefs upon other people."

"We should work to reduce the need to own slaves." 

"We need to create conditions so that plantation owners don't feel forced to own slaves." 

or even better,

"While Candidate X supports a plantation owner's right to own slaves, nobody has worked harder to reduce the need for slavery!" 

Slavery is wrong, Abortion is wrong.  Neither statement requires further qualification.