WASHINGTON, July 31 — Under pressure from President Bush, Democratic leaders in Congress are scrambling to pass legislation this week to expand the government’s electronic wiretapping powers.

Democratic leaders have expressed a new willingness to work with the White House to amend the Foreign Intelligence Surveillance Act to make it easier for the National Security Agency to eavesdrop on some purely foreign telephone calls and e-mail. Such a step now requires court approval.

It would be the first change in the law since the Bush administration’s program of wiretapping without warrants became public in December 2005.

In the past few days, Mr. Bush and Mike McConnell, director of national intelligence, have publicly called on Congress to make the change before its August recess, which could begin this weekend. Democrats appear to be worried that if they block such legislation, the White House will depict them as being weak on terrorism.