In a tale of strange bedfellows, critics on the right and the left are teaming up to fire barbs and legal threats at a new Maryland congressional redistricting map backed by Gov. Martin O’Malley.

O’Malley’s advisory committee released a map this week that moves Maryland voters into new districts to reflect the results of the 2010 Census. The proposal is open to public comment until Tuesday, and then O’Malley (D) will submit the plan in a special session of the General Assembly scheduled to begin Oct. 17.

Most notably, the proposed map would make Rep. Roscoe G. Bartlett’s (R) reelection more difficult by taking a large portion of Frederick County from his 6th District and replacing it with a portion of Democratic-leaning Montgomery County.

Republicans have complained that the map is a gerrymandered effort to achieve a more lopsided advantage for Democrats in the congressional delegation. Meanwhile, a group representing African Americans has threatened to sue because it thinks the proposal does not include enough majority-minority districts.

Bartlett has publicly opposed the map. After meeting with O’Malley on Thursday, he said he wanted to help the governor “strengthen the confidence and trust of Marylanders in Maryland’s delegation in the United States Congress with a redistricting map that respects and accurately reflects the 45 percent of Marylanders who are minorities as well as residents in rural areas.”

Rep. Donna F. Edwards (D), meanwhile, has not commented publicly on the map. But multiple Maryland Democratic sources said she is unhappy that the plan takes away the portion of upper Montgomery County she represents, instead stretching her 4th District east from Prince George’s County into Anne Arundel County.

Adding a layer of potential intrigue, Bartlett and Edwards were seen huddling over maps of the state during House votes Wednesday evening.

“They were literally reviewing maps on the House floor, and not even in some corner,” said a Democratic source who witnessed the meeting and requested anonymity.

Given their shared interest in the subject, Bartlett spokeswoman Lisa Wright said she was “not surprised that they were observed discussing what seemed to be redistricting maps.”

Edwards’s office declined to comment.

For Edwards, giving up Montgomery County would mean losing valuable fundraising turf and voters sympathetic to her reliably liberal voting record. She could be susceptible to an eventual primary challenge from a fellow Democrat in Prince George’s County, just as she herself got to Congress by ousting the incumbent Albert R. Wynn in the 2008 primary.

Edwards is seen as having a potentially bright future in the House Democratic leadership. But if she works overtly with a Republican to undermine a map endorsed by her high-profile Democratic governor — one that could net her party an additional House seat — then that could alienate some colleagues both inside and outside her state.

Rep. Chris Van Hollen (D), whose 8th District would swap Montgomery territory for Frederick, also met with O’Malley on Thursday. A source with knowledge of the conversation said Van Hollen requested “relatively minor changes” to the map.

“Whatever the final district looks like, Congressman Van Hollen looks forward to reaching out and meeting new people,” said Van Hollen spokeswoman Bridgett Frey.

O’Malley spokeswoman Raquel Guillory said the governor had spoken to all eight of the state’s incumbent House members, and “no one is completely happy.”

That is also true of the Fannie Lou Hamer Political Action Committee, a grass-roots group devoted to strengthening minority representation in Maryland. The group has pushed for a map that creates three black-majority districts.

The current map and the proposed map each have two such districts — Rep. Elijah E. Cummings’s (D) 7th District and Edwards’s 4th — while Rep. Steny H. Hoyer’s (D) 5th District is more than 30 percent African American.

That’s not enough for FLH-PAC, and spokesman Radamase Cabrera said that if the current plan passes, “we have every intention of filing legal action” alleging violations of the federal Voting Rights Act.

Cabrera’s group has consulted with the Maryland Republican Party about teaming up for a lawsuit, according to him and a GOP spokesman.

“I’m told Governor O’Malley has higher aspirations,” Cabrera said, referencing the possibility that O’Malley could someday run for president, “and I would hope that he would not be part of a process that dilutes African American voting strength.”

Guillory responded: “The map that has been recommended complies with the letter and the spirit of the law, by maintaining two solidly majority-minority districts and recognizing the growing minority population in the 5th Congressional District.”

Staff writer John Wagner contributed to this report.