AUGUSTA – Democratic and Republican bargainers have tentatively agreed on how to redraw the boundaries of Maine House of Representative districts to reflect a decade’s worth of population shifts around the state.

Participants on both sides had been saying a deal was possible, but the actual accord – subject to review by rank-and-file lawmakers – still came as something of a surprise.

It is unclear whether the two sides will be able to strike similar agreements on the mapping of state Senate districts and on the drawing of congressional district boundaries.

Further negotiations were expected to extend over the weekend in advance of a public hearing scheduled for Tuesday.

The apportionment commission is due to present its plans to the Legislature by Thursday.

“We’re not looking at being cute,” said one Democratic panelist, Rep. Matthew Dunlap of Old Town. “We’re really looking at, at least politically, having competitive districts.”

As shown by the 2000 census, communities across southern Maine grew during the 1990s while population in the north dwindled.

Redistricting must take into account population changes in both the 1st and 2nd Congressional Districts, as well as 151 state House districts and 35 state Senate districts.

“It’s really to give people fair representation,” Dunlap said.

Enactment of a plan by the Legislature requires two-thirds majorities. If lawmakers fail to approve a plan, the task is given to the state supreme court.

The tentative House deal potentially could match four pairs of incumbents in new districts in northern Aroostook County, the areas around Ashland and Skowhegan and in Portland.

In assembling population blocks approximating an ideal of 8,443, the proposed state House district map would split about 15 communities, according to analysts on both sides.

State Senate Republican leader Paul Davis of Sangerville, another panelist, said prospects for two-party support of a unified plan had improved.

“They’re a lot better today than they were two weeks ago,” he said. “It’s certainly not a done deal by any means, but it’s possible.”

Data from the 2000 census released in March 2001 showed that Maine’s population grew by 3.8 percent to 1,274,923 people between 1990 and 2000.

Only four states had lower growth rates over the decade.

York County had the biggest percentage gain of 13.5 percent. Aroostook County lost 15 percent of its population.

New government estimates late last year suggested that more than 16,000 Mainers were among 3.2 million people overlooked across the nation in the 2000 census. A revision including those estimates would put Maine’s population for 2000 at 1,291,649.

The 15-member apportionment commission, which includes seven representatives of each major political party, is being led by a nonaligned 15th member, Professor Donald Zillman of the University of Maine School of Law.