Gov. Martin O’Malley’s redistricting panel released its recommendations for Maryland’s new congressional map Monday, offering a plan that could help Democrats add to their advantage in the state by imperiling the reelection hopes of Rep. Roscoe G. Bartlett (R).

The advisory committee was tasked with drawing a map that reflects the results of the 2010 Census, moving Marylanders across lines to ensure that the state’s eight districts have roughly equal populations. The map will be posted online Tuesday, when a seven-day comment period begins. O’Malley (D) can make adjustments before presenting it to the Democratic-controlled General Assembly, which must approve it.

Democrats hold a 6-to-2 advantage in the congressional delegation, and they hope the new lines could change that to 7-to-1. Bartlett, whose 6th District runs across the top of the state from the West Virginia border to the Susquehanna River, would lose the eastern part of his district and a portion of Frederick County, while adding Poolesville, Gaithersburg and other pieces of western Montgomery County.

In the process, the district would go from one that strongly favors Republicans to one in which Democrats have a narrow edge, based on past elections.

State Sen. Robert J. Garagiola (D-Montgomery), who has emerged as a potential challenger to Bartlett, said he expects to make a decision this month about whether to run for Congress, after the legislature approves the map.

If the final product looks like what the committee presented Monday night, “I think there’s a very good chance that I’d be in,” Garagiola said.

Garagiola said that it appears that about 80 percent of his state Senate district would be inside the new 6th Congressional District.

In Annapolis, Democratic legislators were briefed starting Monday afternoon on the plan by Jeanne Hitchcock, chairwoman of the governor’s redistricting panel.

The committee approved the map Monday morning in a 4-to-1 vote, with former delegate James King (R-Anne Arundel) providing the only dissenting vote.

Hitchcock said the panel worked with “a delegation map that is currently convoluted in its configuration. Everyone wanted to do our best to correct that.”

Although O’Malley is free to make changes to the map, Hitchcock said, “I have no reason to believe he will change it significantly.”

Maryland’s other congressional Republican, freshman Rep. Andy Harris, would see his Eastern Shore-based 1st District become safer, as it no longer crosses the Chesapeake Bay to include part of Anne Arundel County. It is not clear whether Frank Kratovil (D) — who held the seat for two years before losing it to Harris and now works as the assistant deputy state’s attorney in Prince George’s County — would consider a rematch under the new lines.

Prince George’s and Montgomery gained population over the past decade, while the City of Baltimore shed residents. House Speaker Michael E. Busch (D-Anne Arundel), a member of the redistricting committee, said that about 70 percent of residents would remain in the same congressional district under the new map.

“Our goal was to keep as many people in their current congressional districts as we possibly could,” Busch said.

Senate President Thomas V. Mike Miller Jr. (D-Calvert), an advisory committee member, said that overall “the change is quite modest.”

“The map is much more aesthetically pleasing,” Miller said. “All in all, the map will be better received than the map 10 years ago. We did the very best we could to try to reach a consensus.”

Miller and Busch noted that none of the sitting congressman would be pitted against each other next year, as has been the case in some other states’ redistricting processes.

The new map has been the subject of speculation on Capitol Hill and in Annapolis for months, as Democratic lawmakers negotiated among themselves and potential draft lines were leaked to the media. As recently as Friday, Democrats were said to be considering a map that would attempt to oust Bartlett and Harris.

Instead, Democrats have chosen to target only Bartlett. Privately, some Democratic strategists in the state hope the new map will prompt Bartlett, who turned 85 in June, to retire after two decades in Congress. He has given no indication that he will do so.

Bartlett’s office declined to comment Monday evening on the proposed district lines.

Responding last month to a leaked map draft that also targeted Bartlett, Maryland Republican Party Chairman Alex Mooney said that the proposal was “a backroom deal and is an insult to the people of Maryland.”

Rep. Donna F. Edwards’ (D) 4th District would remain largely based in Prince George’s, but she would give up the portion of Montgomery she represents and move east toward Anne Arundel.

Rep. Chris Van Hollen (D) would surrender some of Montgomery from his 8th District to Bartlett and take portions of eastern Frederick County and western Carroll County. His district would lose some Democratic voters but remain safe for the incumbent.

Rep. Steny H. Hoyer’s (D) 5th District would also stay secure for Democrats.

In a special session starting Oct. 17, O’Malley will introduce the map as a piece of legislation. Busch said he expects the session to last no more than a week and not address anything other than congressional redistricting. Busch said he had heard no more from O’Malley about the prospect of a jobs bill that the governor floated recently.

Busch said the decision to alter the 6th District was based largely on population growth in that part of the state. He acknowledged that the result would be a district more winnable for Democrats than before.

“You’re going to have a very competitive 6th District, where you didn’t in the past,” Busch said.

Asked why O’Malley’s committee wasn’t more aggressive in crafting districts favorable to Democrats, Busch said: “You try to have a fair reflection of what the state is like.”

Some African Americans have said they are underrepresented in the current delegation. Busch said Maryland will continue to have two majority-minority districts — the 4th and the 7th — and the likelihood of another — the 5th — “over the next decade.”

(Office of Governor Martin O’Malley)