Boeing reiterated in a statement late Tuesday that it had “full confidence” in the 737 Max 8. It noted that the F.A.A. had taken no action and “based on the information currently available, we do not have any basis to issue new guidance to operators.”

Two United States airlines fly the 737 Max 8 aircraft and both said they planned to keep flying. Southwest Airlines has 34 of the planes and American Airlines has 24. The airlines have said they have analyzed data from their thousands of flights with the jets and found no reason to ground them.

“We don’t have any changes planned,” Southwest said in a statement. “We have full confidence in the aircraft,” American said.

The growing pressure left Boeing in an increasingly unfamiliar position. The company, a major military contractor, has close ties with the American government, and the F.A.A. in particular.

[Three generations of a Canadian family died in the Ethiopian plane crash.]

Boeing is a major lobbying force in the nation’s capital. Its top government relations official is a veteran of the Clinton White House, and last year, the company employed more than a dozen lobbying firms to advocate for its interests and spent $15 million in total on lobbying, according to the Center for Responsive Politics.

The company, through its political action committee, funnels millions of dollars into the campaign accounts of lawmakers from both political parties. A list of a year’s worth of political spending on Boeing’s website stretches on for 14 pages, listing campaign contributions to lawmakers ranging from a city councilman in South Carolina to Representative Nancy Pelosi of California, who is now the House speaker.