Romney, a Republican who was his party’s presidential candidate in 2012, joined similar calls from senators Richard Blumenthal and Diane Feinstein, who are Democrats.
The FAA declined to comment on the senators’ statements.
Regulators around the world including the United Kingdom, Australia, France, Ireland and Singapore, and a growing number of airlines, are grounding the 737 MAX 8 in the wake of two fatal crashes in five months.
Boeing in a statement on Tuesday did not directly address the senators’ comments but said it has “full confidence in the safety of the MAX” and noted the FAA has not mandated “any further action at this time.”
Boeing added it understands “regulatory agencies and customers have made decisions that they believe are most appropriate for their home markets.”
The FAA told international carriers on Monday there was no need to ground the plane but it would mandate a software upgrade and training changes by April that Boeing confirmed late on Monday it will roll out in the coming weeks.
US Transportation Secretary Elaine Chao told reporters on Monday that regulators would not hesitate to act if they find a safety issue.
“If the FAA identifies an issue that affects safety, the department will take immediate and appropriate action,” Chao said. “I want people to be assured that we take these incidents, these accidents very seriously.”
US President Donald Trump, who has been briefed on the Ethiopian Airlines crash according to administration officials, on Tuesday tweeted that “Airplanes are becoming far too complex to fly. Pilots are no longer needed, but rather computer scientists from MIT.”
He added “complexity creates danger. All of this for great cost yet very little gain. I don’t know about you, but I don’t want Albert Einstein to be my pilot. I want great flying professionals that are allowed to easily and quickly take control of a plane!”
The White House did not immediately respond to a request for comment about whether Trump was referring to a specific aeroplane.