WASHINGTON — For years, intelligence officials have tried to debunk what they called a popular myth about the National Security Agency: that its electronic net routinely sweeps up information about millions of Americans. In speeches and Congressional testimony, they have suggested that the agency’s immense power is focused exclusively on terrorists and other foreign targets, and that it does not invade Americans’ privacy.

But since the disclosures last week showing that the agency does indeed routinely collect data on the phone calls of millions of Americans, Obama administration officials have struggled to explain what now appear to have been misleading past statements. Much of the attention has been focused on testimony by James R. Clapper Jr., the director of national intelligence, to the Senate in March that the N.S.A. was not gathering data on millions of Americans.

When lawmakers returned to the Capitol on Tuesday for the first time since the N.S.A. disclosures, however, the criticism was muted.

In carefully delivered statements, Speaker John A. Boehner of Ohio; Senator Harry Reid of Nevada, the majority leader; and Senator Mitch McConnell of Kentucky, the Republican leader, all said the programs were authorized by law and rigorously overseen by Congress and courts.