The Arizona senator focused his address on an exchange at the Saddleback forum on faith last week.

“[Rick Warren] asked my opponent a very serious question,” said McCain, referencing the pastor and author who hosted the forum. “He wanted to know at what point, in my opponent's view, does a baby have human rights? Sen. Obama thought about it for a moment, and came back with the reply that the question was, quote, ‘above my pay grade’.”

The exchange, McCain argued, shows that “when it’s time for straight answers, clear conviction, and decisive action, suddenly all of these responsibilities are -- well, as he puts it, ‘above my pay grade’.”

McCain, following a week of media speculation that he might pick a running mate who supports abortion rights, in his address repeatedly emphasized his anti-abortion stance. The GOP’s conservative base had issued warnings to their party’s candidate following rumors that McCain might be considering Sen. Joseph Lieberman (I-Conn.) or former Homeland Security Secretary Tom Ridge as running mate, both of whom support abortion rights.

McCain did squeeze in a quick joke about Obama's vice presidential candidate, who was named after the radio address was recorded.

“All the talk today is about my opponent's selection of his running mate,” McCain said.”To his new running mate, my congratulations and I'll get back to you real soon on your debating opponent.”

McCain is expected to name his own running mate by the start of the Republican National Convention on Sept. 1.