Sinclair Broadcast Group defended its proposed acquisition of Tribune Media as being in the public interest and vital to the health of broadcast television, amid a flood of criticism that the deal would consolidate too much power into one media giant.

In a 173-page filing submitted to the Federal Communications Commission (FCC) on Tuesday, Sinclair wrote that such consolidation is necessary as broadcast companies grapple with a changing media industry that has been upended by online streaming services.

"Sinclair firmly believes in the mission of local broadcasting and this filing fully explains the public interest benefits that this transaction will provide as a result of the efficiencies and scale created by the combination of Sinclair and Tribune," Chris Ripley, Sinclair's president and CEO, said in a statement. "This acquisition will help to ensure the future of the free and local television model for both Tribune and Sinclair's local communities."

Critics of the deal include Democrats, public interest groups, the cable industry and even competing conservative media outlets.

The Coalition to Save Local Media, which represents groups on that side, said that Sinclair's filing did little to ease their concerns.

"Sinclair-Tribune's response today leaves too many questions unanswered about the public interest harms caused by the proposed merger," the group said in a statement. "There is no basis for the FCC to allow this merger to proceed. The FCC and Department of Justice should reject this merger."

Sinclair owns 173 local television stations across the country, serving an estimated 38 percent of U.S. households - the largest reach of any broadcast station operator. If its deal with Tribune goes through, the combined broadcasting juggernaut would reach 72 percent of the nation's households.

Opponents argue that such concentrated media power would stifle smaller, independent outlets.

Last week, a trio of House Democrats - Reps. Frank Pallone Jr. (N.J.), Mike Doyle (Pa.) and Diana DeGette (Colo.) - sent a letter to FCC Chairman Ajit Pai asking him to explain what they see as "preferential treatment" toward Sinclair from the agency, which in April cleared a regulatory roadblock that would have impeded the deal.

"We hope this letter will serve as an opportunity to respond to reports suggesting you have failed to exercise adequate independence as FCC Chairman and that may have resulted in the agency giving unusual and possibly preferential treatment to Sinclair," the Democrats wrote.

In April, Pai pushed through a rule reinstating what's known as the UHF discount. The rule, which had been repealed last year under the Obama administration, discounts the audiences of ultra-high frequency television stations toward the cap on the amount of households broadcasters can reach.

That limit is currently 39 percent, but Pai has said that the agency will consider raising it by the end of the year.

This story was updated at 2:01 p.m.