Distract Crouch for as long as possible. Harry wasn't sure exactly what he'd need to say to him to do that, since simply asking what he wanted wasn't likely to get an answer that would have much in terms of... wiggle room. Crouch hadn't given him any, so far.
But people's lives were at stake, and the more time they had, the better.
"I'll do my best," he said. At least with an actual agreed upon objective in mind, he could keep himself out of trouble with the journals, right? "I'll let you know everything he says."