WASHINGTON— This week brings increased pressure on U.S. lawmakers to reform or reauthorize the National Security Agency’s ability to gather domestic telephone records for anti-terrorist purposes, because the program expires at the end of this month.

A federal appeals court ruled so-called “bulk metadata” collection illegal but did not order a stop to the program launched in the aftermath of the September 11, 2001, terrorist attacks on the United States.

Even before last week’s court decision, some in Congress were urging reform of domestic spying.

“I believe we have to protect our national security, but we also have to protect our civil liberties that make us unique as a country,” Democratic Senator Patrick Leahy said.

NSA leaks

Exposed by fugitive former NSA contractor Edward Snowden, the program caused a firestorm when Americans learned of vast telecommunications monitoring by a shadowy U.S. agency.

Last year, President Barack Obama pledged what he called “a new approach.”

“The United States is not spying on ordinary people who do not threaten our national security, and we take their privacy concerns into account in our policies and procedures," Obama said then.

Moments after the court ruling last week, several Republicans rushed to defend the program, which reportedly collects and stores phone records but not the content of calls made.

“The NSA can find connections from known terrorists overseas and connect them to potential terrorists here in the United States. Critics of the program either want to do away with it or make it much more difficult to use," Senate Majority Leader Mitch McConnell said.

Ending the program is unthinkable, Senate Intelligence Committee Chairman Richard Burr said. “We are going to keep America safe. We are not going to revert back to where we are susceptible to another 9-11," he said.

Others see a threat to privacy.

“I say the phone records of law-abiding citizens are none of their damn business," Republican Senator Rand Paul. He also announced in early April he is running for the Republican presidential nomination in 2016.

Commitment to transparency

That the debate is unfolding at all shows America’s commitment to transparency, President Obama said.

“No one expects China to have an open debate about their surveillance programs, or Russia to take the privacy concerns of citizens into account. But let us remember: we are held to a different standard precisely because we have been at the forefront of defending personal privacy and human dignity," he said.

Many expect the Supreme Court will ultimately decide the constitutionality of bulk data collection.

In the meantime, Congress could extend the NSA program or reform it. Lawmakers of both parties say the stakes for national security, and civil liberties, are high.