The CEOs of United and Continental airlines are telling Congress their merger will be good for consumers, airline employees and the small communities that rely on them for service.

United's Glenn Tilton told the Senate Judiciary Committee Thursday that the new airline will improve its profitability through efficiencies, not higher fares. Continental's Jeffery Smisek pledged that the nearly 150 small communities and metro areas served by the carriers won't lose service.

Other witnesses said the merger will likely diminish competition.

Similar concerns about competition were raised by the 2008 merger of Delta Air Lines Inc. and Northwest Airlines, but the Bush administration's Justice Department quickly approved the deal.