No witnesses have been announced for the hearing to be held by the Senate Judiciary Committee's subcommittee that oversees antitrust issues announced on Wednesday. However T-Mobile Chief Executive John Legere and Sprint CEO Marcelo Claure met with the U.S. Justice Department and the Federal Communications Commission earlier this month to tout the proposed tie-up and are likely to testify, officials said.

"Few industries touch Americans’ daily lives as much as the wireless market,” Senator Mike Lee, a Republican who chairs the subcommittee said in a statement. "I want to make sure that the proposed merger between T-Mobile and Sprint benefits consumers in a manner consistent with existing antitrust law."

Senator Amy Klobuchar, the ranking Democrat on the panel, said in a statement the "combination of T-Mobile and Sprint raises serious antitrust issues."

"Competition among the four largest cell phone carriers has led to lower prices, better service and more innovation. That’s why it’s critically important that we hold a hearing to ask serious questions about how this consolidation could affect American consumers," Klobuchar said.

The deal capped four years of on-and-off talks between the third and fourth largest U.S. wireless carriers, setting the stage for the creation of a company with 127 million customers that will be a more formidable competitor to the top two wireless players, Verizon Communications Inc and AT&T Inc.

A prior round of merger talks between the companies ended unsuccessfully in 2014 after the administration of then-U.S. President Barack Obama expressed antitrust concerns.

T-Mobile and Sprint said they expected to complete their deal no later than the first half of 2019, an ambitious goal given the intense U.S. regulatory scrutiny it will be subjected to, analysts have said.

(Reporting by David Shepardson; Editing by Bill Berkrot)

By David Shepardson