Senator Barack Obama (D-IL) says that deciding when life begins is "above my pay grade". That seems an evasive answer for a U.S. Senator, but it's absolutely a horrendous answer for a Presidential candidate. While it may be above your pay grade now, it's not above the pay grade of the job you're trying to obtain.
Besides that, it's clearly an answer to keep from scaring away pro-lifers that might be supporting him. Obama's record on this issue is quite clear.
Senator John McCain gave a quick and unequivocal answer:
He said a baby’s human rights began “at the moment of conception … I have a 25-year pro-life record.”
The difference here is that the "new kind of politician" gave an evasive and very calculated answer, while the career politician gave the straightforward unafraid one.