The U.S. wireless industry continues to be fixated by a potential merger of T-Mobile and Sprint, but whether a tie-up would get the nod from federal regulators is still far from clear.

Bloomberg reported recently the two carriers are “putting the finishing touches” on a final agreement that is expected to be announced when they report quarterly earnings later this month. A breakup fee isn’t expected to be included in any final pact, minimizing risks for both carriers should the deal not gain regulatory approval.

Industry insiders generally agree that approval is far from a done deal. And the odds of approval may be significantly slimmer if a deal isn’t consummated by the time midterm elections are held in November 2018, according to Matthew Niknam of Deutsche Bank.

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"Cable companies (and other new entrants appear less interested in outright ownership of wireless assets near-term, leaving Spring/T-Mobile with limited outside options to increase scale at a time when larger peers (AT&T and Verizon) are competing more aggressively. There also may be greater incentive for both sides to evaluate a potential deal sooner rather than later, given the risk that deal approval may slip beyond mid-term elections in late 2018 (with the risk that more populist/less corporate-friendly sentiment may become more pervasive in D.C.) In fact, we note that the Democrats’ ‘Better Deal’ agenda (unveiled in July 2017, targeted towards 2018 elections) highlights ongoing corporate consolidation as a threat to U.S. consumers, and proposes sharper scrutiny of potential deals,” Niknam wrote this morning in a note to investors.

“We remain very bearish on the prospects for deal approval (regulatory risk), though we expect derivative impacts (on an announcement to include positive reactions for Verizon/AT&T (more disciplined wireless market) and negative impacts for the towers (site rationalization, customer concentration),” Niknam continued.

Indeed, eight Senate Democrats have already asked regulators to look into the potential impact of a merger between T-Mobile and Sprint, The Hill reported late last week. “Beginning an investigation into a merger of T-Mobile and Sprint now will allow your agencies to quickly, but fully, review the agreement if it is announced,” the legislators wrote in letters to the Department of Justice and the FCC, The Hill said.

The carriers may be forced to make significant concessions to gain approval of a tie-up, as Barclays noted last month. Those concessions could include spinning off some spectrum, which could pave the way for Dish Network or another company to elbow its way into the wireless market.

Cowen & Company Equity Research last month pegged the chance of an announced deal between the two players at 60% to 70%, down from a previous estimate of 80% to 90%, and said the chance of approval would be roughly even. Those odds may be much longer if a deal isn’t closed by next November.