There is some good reporting here by the Washington Post about the circumstances of Clapper's testimony to Congress. Readers here who know my comments know that I'm not fully happy with how Snowden chose to disclose information from inside NSA, and particularly not about his travel to China (Hong Kong) and Russia, but I think Snowden raises a fair point here. There is some genuine difference of opinion among Americans about how Clapper's statement to Congress should be characterized (whether "lie" or "erroneous statement") and plenty of us who agree with another comment here posted before mine that two wrongs don't make a right. Every national government in the civilized world needs an intelligence-gathering agency that can operate with some degree of operational secrecy.
I think Congress is unsure about how to proceed on this issue because not all members of Congress are of one mind about what is best for the country in administration of NSA. I categorically reject the assertion that Congress is still moving forward slowly to change NSA oversight because "NSA has Congress by the balls." Nope. One of the most common kinds of comments here on Hacker News about issues like this is a comment that ASSUMES that if government leaders are under pervasive surveillance they are all afraid of blackmail. But I don't believe that, because some government leaders and some political candidates are essentially shameless. Even after they are caught (by old-fashioned journalism, or by a jilted lover or some unrelated criminal investigation) doing something unsavory, they are still willing to run for office, and SOME ARE REELECTED. United States Senator David Vitter was reelected in 2010 even after a scandal involving behavior that I would consider shameful,[1] and the antics of former DC mayor Marion Barry[2] are probably still notorious enough that they don't need further discussion here. In short, I call baloney on the idea that NSA can keep politicians on its leash simply by knowing their secrets. Some politicians have PUBLIC lives full of dirt, and still get elected and influence policy anyway.
The other reason I don't believe this HN hivemind theory of politics is that I by no means assume that everyone in politics lacks personal integrity. Some politicians, I am quite sure, could have all their secrets revealed only to have voters think "Why is that person such a straight-arrow? Why not have some fun once in a while?" The simple fact is that there is value system diversity in the United States electorate, and there is personal conduct probity variance among United States politicians, and there isn't any universal way to unduly influence politicians merely through even the most diligent efforts to discover personal secrets. If politicians think that NSA is going too far (as evidently several politicians from more than one party do think), then they will receive plenty of support from the general public to rein in the surveillance. (Obligatory disclaimer: Yes, I am a lawyer, who as a judicial clerk for my state's Supreme Court used to review case files on attorney misconduct, and, yes, some of my law school classmates are elected officials, including one member of Congress. I am absolutely certain that there are enough politicians ready to mobilize to roll back NSA surveillance programs if they really think the programs are excessive in their scope.)
[1] https://en.wikipedia.org/wiki/David_Vitter#D.C._Madam_scanda...
[2] https://en.wikipedia.org/wiki/Marion_Barry#1990_arrest_.26_d...