There’s no guarantee that Clapper and crew will provide a reasonable answer. Both the House and civil liberties groups have made similar requests in recent years, and officials have stymied their efforts each time. Also, there’s no guarantee that the data will be useful. Remember how companies are only allowed to provide vague National Security Letter numbers? Yeah. While you’re unlikely to ever get exact numbers (they can occasionally say a lot about who’s being targeted), overly broad figures might be pointless.
The House does have one advantage on its side: it controls the legislation that lets this surveillance happen. The FISA section that allows the data collection expires at the end of 2017, and Congress could let it lapse if it doesn’t get a satisfactory answer. With that said, similar threats have been made before, to little effect. Politicians may have to prove that their ultimatum has teeth in order to get results.