Construction workers in the United Mine Workers union could reach a tentative agreement with the Associated Bituminous Contractors early this week, removing a possible obsticle to full resumption of soft-coal production in the East and Midwest, a UMW spokesman said yesterday.

"There is a possibility that we could have an agreement early this week. Things are beginning to look a little better," union spokesman Eldon Callen said of the UMW-ABC talks under way yesterday at the Capital Hilton. The two sides, whose negotiations affect about 11,000 members of the 160,000-member union, have been meeting daily since June 1 in an attempt to draft a new contract.

Miners in the union, who bargain separately from the construction workers, voted Saturday to accept a new 40-month pact with the Bituminous Coal Operators Association, thus ending a strike that began March 27.

The miners were scheduled to return to work at 12:01 a.m. today, but there was concern over the weekend that resumption of mining operations could be delayed if the construction workers, who also walked out when their original three-year contract expired March 27, decide to picket mines where construction is in progress.

"The construction workers legally can put up a picket line wherever they have construction work at a mine," Callen said yesterday. "This could affect some mines, but it certainly won't affect all of them." Callen said he could not give specific figures on how many mines might be affected.

"You would have pickets only if you have construction workers at that mine," he said. "We have 11,000 construction workers, but not all of the mines have construction going on. At some mines, you have only one or two construction workers."

"In a lot of areas," he added, "construction workers may wait a while before putting up any picket lines in order to allow thier other union brothers and sisters to get some working time in."

The UMW-Bituminous Coal Operators Association negotiations are the so-called "main table" in union-management bargaining in the soft coal industry. The UMW-ABC bargainers traditionally settle their differences after the "main table" contract has been approved, although union officials contendthey were trying to get simultaneous mining and construction agreements in the last round of negotiations.

Even without picket lines, some mines may not be able to reopen until construction crews return to their jobs to correct safety problems such as weakened structures that may have developed during the lengthy strike, according to industry management sources interviewed over the weekend.

"A lot of people believe that all you have to do in mining is dig a hole or strip a mountain and start hauling out the coal," and Dennis P. Duncan, superintendent of the western division of the Blair Electric Service Co., a Pennsylvania-based mine construction firm that operates with union and nonunion labor.

"But somebody has to build the mine first, and somebody has to maintain the structure after it's built. You just can't go in there and start digging without proper construction," said Duncan, whose division is based in Gellette, Wyo.