The White House, under fire from closest allies, is taking a closer look at the National Security Agency's vast data collection. NBC's Andrea Mitchell reports.

The United States is scrambling to soothe some of its closest allies, angered as one report after another details vast American spying — including gathering data on tens of millions of phone calls in Spain in a single month.

The latest report, published Monday in the Spanish newspaper El Mundo, said that the National Security Agency had collected information on 60 million calls in that country last December.

It followed reports in the last week that the United States spied on leaders of at least 35 countries, and even bugged the personal cellphone of German Chancellor Angela Merkel.

Jay Carney, the White House press secretary, said Monday that a White House review of intelligence-gathering would be complete by year’s end, and that it would address how to balance national security and privacy.

But he stressed: “The work that’s being done here saves lives and protects the United States and protects our allies, and protects Americans stationed in very dangerous places around the world.”

"We need to make sure that we're collecting intelligence in a way that advances our security needs and that we don't just do it because we can," he said.

He declined comment on stories about specific NSA spying activities.

German intelligence chiefs are preparing to visit Washington this week to demand answers, and the German Parliament on Monday called a special session for Nov. 18 to talk about NSA spying.

At the Capitol, a delegation of European Parliament officials met with Rep. Mike Rogers, R-Mich. and the chairman of the House Intelligence Committee, to discuss the spying reports. Several who spoke to reporters later voiced frustration, and questioned whether the United States was legitimately trying to fight terrorism.

“If we don’t get the explanations, I don’t think we can trust on the reliability of the U.S. in these questions,” said Axel Voss, a German member of the European Parliament. “But if they are now starting to talk to us and explaining to us why and how and what data and so on, then it might be very helpful, and we can regain trust and reinstall trust again.”

He added: “But it’s getting more and more difficult.”

President Barack Obama has had to apologize to Merkel and to the presidents of France and Brazil. The Brazilian president was so angry she canceled a state visit.

Unhappy with the Obama administration after learning that the U.S. has spied on dozens of European leaders, the European Union is threatening to cancel pending trade talks. NBC's Andrea Mitchell reports.

Sen. Dianne Feinstein, D-Calif., the Senate Intelligence Committee chairwoman, on Monday called for a "total review" of intelligence programs and said she is "unequivocally opposed" to NSA surveillance of friendly foreign leaders. She suggested that Congress was unaware of such activities.

"With respect to NSA collection of intelligence on leaders of U.S. allies-including France, Spain, Mexico and Germany-let me state unequivocally: I am totally opposed," Feinstein said in a statement. "It is my understanding that President Obama was not aware Chancellor Merkel's communications were being collected since 2002. That is a big problem," she said.

In a statement, another member of the committee, Sen. Susan Collins, R-Maine, said she knew of “no justification for the administration's collection of intelligence on the leaders of our closest allies, such as Chancellor Angela Merkel.”

Collins said she is meeting with the German ambassador on Tuesday night and will express directly that monitoring Merkel’s phone calls was wrong.

State Department spokeswoman Jen Psaki acknowledged that U.S. spying has "created significant challenges in some of our most important partnerships," but added that the U.S. has "not seen an across-the board impact on our foreign policy."

"Some partners have raised concerns with us, and we have some work to do, certainly, in those relationships," she said. The U.S. government is "open to discussions with our close allies and partners about how we can better coordinate on our intelligence efforts" as a result, she said.

Former White House press secretary Robert Gibbs tells TODAY's Savannah Guthrie the Obama administration should consider whether spying on world leaders is worth the intelligence they are getting, saying the latest revelations are an embarrassment.

The Obama administration and its defenders say that most of the spying is legitimate, for the protection of the United States and its allies.

Vice President Joe Biden expressed optimism that any lingering concerns the German leader has over snooping can be worked out.

"I'm confident that Merkel still has faith and confidence in the president as well as in the United States," Biden said Monday.

In a statement Sunday night, U.S. National Security Council spokeswoman Caitlin Hayden said that a White House review is examining “the way that we gather intelligence to ensure that we properly account for the security concerns of our citizens and allies and the privacy concerns that all people share, and to ensure that our intelligence resources most effectively support our foreign policy and national security objectives.”

Rep. Peter King, R-N.Y. and a member of the House Intelligence Committee, said on NBC’s “Meet the Press” that the administration should not apologize or be defensive.

“The reality is the NSA has saved thousands of lives, not just in the United States but in France, Germany and throughout Europe,” he said. “We’re not doing it for the fun of it. This is to gather valuable intelligence, which helps not just us but also helps the Europeans.”

The reports have come from documents leaked by Edward Snowden, the fugitive former NSA contractor. The only clear denial from the NSA has concerned a British report that said that Obama was told three years ago that the agency was eavesdropping on Merkel.

The German newspaper Der Spiegel reported that Obama told Merkel that he would have halted the hacking if he had known about it.

Snowden's intermediary, journalist Glenn Greenwald, speaking from Brazil, told NBC News on Monday that it’s believable that Obama didn't know about the spying.

"Unfortunately, it is credible because the NSA has become this rogue agency that really does go off on its own and do whatever it wants,” Greenwald said. “And I'm not sure which is scarier that the president did know and approved it and now is lying about it, or that he didn't know and the NSA just took it upon itself to do that without their commander in chief being aware."

Juan Medina / Reuters The U.S. ambassador to Spain, James Costos, leaves the foreign ministry after being summoned to a meeting with Spain's European Secretary of State in Madrid on Monday.

The consequences may be economic, not just diplomatic. The European Union, the United States’ largest trading partner, is threatening to cancel trade talks over the revelation.

In the meantime, the U.S. is left to deal with furious allies without knowing what Snowden will reveal next.

“When we’re doing this on Germany, on France, on Great Britain and other nations that we’ve been allied with in fighting Al Qaeda, in invading Libya together, these kinds of things just trample trust,” said Steve Clemons, who writes frequently on foreign policy.

Robert Gibbs, a former press secretary for the Obama administration, told TODAY on Monday that “clearly, damage has been done.”

“I think we have to evaluate whether the costs of the methods of gathering some intelligence greatly exceeds the benefit of that intelligence, particularly when we’re listening in to, apparently, some of our very closest allies,” he said.

Kasie Hunt, Catherine Chomiak, Kelly O'Donnell and Jeff Black of NBC News contributed to this report.

This story was originally published on