The normally voluble Senator John McCain found himself at a loss for words Wednesday when he was asked aboard his campaign bus on its way to Portsmouth, Ohio, whether he thought it was fair that some health insurance companies covered Viagra but not birth control.

“I don’t usually duck an issue,” he said, “but I’ll try to get back to you.”

One of Mr. McCain’s top supporters, Carly Fiorina, raised the issue this week when she was explaining his plan to encourage people to shop around for health insurance policies. “There are many health insurance plans that will cover Viagra but won’t cover birth-control medication,” Ms. Fiorina said, according to The Washington Post. “Those women would like a choice.”

That prompted Naral Pro-Choice America to note that Mr. McCain had voted against a 2005 bill requiring health insurance companies to cover birth-control pills as well as Viagra. Mr. McCain said he did not recall the vote.

One aide to Mr. McCain said later that the senator did not support mandates for coverage of certain drugs, and that the bill he had voted against also expressed support for using tax money to promote the use of emergency contraceptives, which Mr. McCain opposed.