A State Department official offered condolences to the family, but did not identify the citizen.
Sen. Chuck Grassley's office said the Iowa Republican's source is "well-known" to Democratic staff.
The airstrike hit a checkpoint in March.
Lawmakers want to know if he agrees with Attorney General Loretta Lynch.
The majority leader started the fast-track process for a House-passed bill.
Sen. Jack Reed (D-R.I.) blocked McCain's request with "great reluctance."
Alissa Starzak was pressed on how Senate aides obtained a secret CIA document.
The presidential candidate's push thwarted a housing and transportation bill.
The bill would have blocked refugees from nations with "terrorist-controlled territory."
The rules of engagement have been criticized as too restrictive.
But the Iowa Republican added a hold on a top State Department nominee.
States will “explore all legal options," a trio of attorneys general promised.
Rep. Yoho wants to allow governors to reject Syrian refugees.
A new poll finds large majorities in support of boots on the ground.
Democrats are pushing to block those on the terror watch list from buying guns.
Lawmakers have focused on the visa waiver program in the wake of the Paris attacks.
Ex-Secretaries Napolitano and Chertoff called the current process "thorough and robust."
Rep. Ryan Zinke (R-Mt.) helped to co-author the bill, which passed 289-132.
McCain has long pushed for boots on the ground against ISIS.
The statement did not go into details, such as whether the casualty was a U.S. casualty.
"I've been disappointed by Republican fear mongering and bigotry," he said.
Rep. Ryan Zinke (R-Mont.), a former Navy SEAL, said U.S. commanders' hands are tied.
He wants to block new refugees from getting access to public benefits.
The statement is the White House's clearest public acknowledgment of the group’s role.