PORTLAND — Representatives of two striking unions and company officials at FairPoint Communications were scheduled to return to the bargaining table Tuesday at the request of a federal mediator, but both sides said they entered the discussion with few expectations.

The meeting in Boston was called by a federal mediator assigned to the case. The unions said that the meeting aimed to “jump-start” negotiations over a contract that expired in August.

Angelynne Beaudry, a spokeswoman for FairPoint, said when the meeting was announced last week that “no assumptions should be made” about what will come from the meeting. Peter McLaughlin, a lead negotiator for the International Brotherhood of Electrical Workers, said in a telephone interview last week that there’s no indication that the sides were any closer to a deal heading into Tuesday.

Negotiations stopped Aug. 28 when the company declared an impasse in talks, saying that the union had stopped bargaining. The International Brotherhood of Electrical Workers and Communications Workers of America dispute that and in response filed a complaint that is still pending with the National Labor Relations Board.

Union officials said they had offered about $218 million in concessions during the bargaining process and that the company’s proposal that it imposed on workers after declaring the impasse sought to reduce its costs by about $700 million.

McLaughlin said last week that the union remains willing to negotiate but has said the company has withheld its financial backing for requesting that amount of concessions from the union, which is the subject of another complaint the union has filed with the NLRB.

The key issues in the negotiations are over bringing in contract workers and shifting to a health care plan that shifts part of the premiums to workers and has higher deductibles.