We can look at this in one of two ways. Maybe only 47 of the current 100 US Senators didn’t know enough about the NSA surveillance programs to consider themselves fully informed and satisfied that the intelligence community doesn’t cross the line when it comes to spying on Americans. Or, perhaps 53 of the current 100 US senators don’t really care whether the NSA is spying on Americans — at least not enough to put off plans for a long weekend:

A recent briefing by senior intelligence officials on surveillance programs failed to attract even half of the Senate, showing the lack of enthusiasm in Congress for learning about classified security programs. [WATCH VIDEO]

Many senators elected to leave Washington early Thursday afternoon instead of attending a briefing with James Clapper, the Director of National Intelligence, Keith Alexander, the head of the National Security Agency (NSA), and other officials.

The Senate held its last vote of the week a little after noon on Thursday, and many lawmakers were eager to take advantage of the short day and head back to their home states for Father’s Day weekend.

Only 47 of 100 senators attended the 2:30 briefing, leaving dozens of chairs in the secure meeting room empty as Clapper, Alexander and other senior officials told lawmakers about classified programs to monitor millions of telephone calls and broad swaths of Internet activity. The room on the lower level of the Capitol Visitor Center is large enough to fit the entire Senate membership, according to a Senate aide.

This was the third briefing for Congress on this topic in a week, so perhaps some of these members felt they already had enough information to feel comfortable with the programs. Tom Coburn explained that he has already been fully briefed as a member of the Senate Intelligence Committee and didn’t need to stick around. That didn’t cut much ice with committee chair Dianne Feinstein, who vented considerable frustration at the poor attendance:

“It’s hard to get this story out. Even now we have this big briefing — we’ve got Alexander, we’ve got the FBI, we’ve got the Justice Department, we have the FISA Court there, we have Clapper there — and people are leaving,” she said.

I don’t often agree with Feinstein, but she’s spot-on here. Isn’t a briefing on whether the executive branch is abusing the First and Fourth Amendments worth canceling a flight and staying over until Friday? Father’s Day is Sunday, after all, not Friday.

Did the briefing work? Politico notes that the biggest Senate critics haven’t reacted yet, and some others have said that the NSA and DNI should have been more transparent earlier to avoid the kind of reaction seen over the last week:

Still, some of the harshest critics of the NSA’s programs declined comment following the briefing, including Sens. Rand Paul (R-Ky.) and Ron Wyden (D-Ore.). Paul held a news conference just minutes before the briefing in which he indicated he might help sue the government over surveillance; Wyden and Sen. Mark Udall (D-Colo.) expressed public skepticism with Alexander’s assertions that phone records may have helped avert “dozens” of terrorist events.

And several senators declined to discuss the tone of the meeting, even when granted anonymity. But even with critical public statements being lobbed at Alexander and Clapper about the surveillance programs through media outlets, Sen. Martin Heinrich (D-N.M.) described the tone as “constructive.” …

Still, there’s a sense that more should have been done sooner so that senators could have been been prepared for the storm of questions that followed media reports on the NSA programs. Briefings were made available on the telephone records programs to senators in the past, but it was up to individual members to attend them.

“It would have been helpful a long time ago. Their argument now is this has been vetted by Congress and the courts. And to some degree that’s true but in very limited ways,” said Sen. John Thune of South Dakota, a member of Republican leadership. “Their attempts now are kind of after the fact. Very reactionary.”

“They have not done a particularly good job in explaining it to the American people,” said Sen. Bernie Sanders (I-Vt.).

And they still haven’t.