Democrats on the Montgomery County Council find Gov. Martin O’Malley’s proposed gerrymandering of their home turf so outrageous that they are coming out publicly against it Tuesday.

What’s more, they are raising the political stakes by complaining that the plan is unfair to blacks, Latinos and Asians in Montgomery, where the latest census shows minorities together have become the majority.

It’s one thing for the Maryland Democratic political establishment to redraw U.S. congressional districts to stick it to the Republicans (as it is aiming to do, blatantly). The state is so overwhelmingly Democratic that GOP objections pose little risk to O’Malley & Co.

But it’s another thing to alienate minorities and good-government advocates in Montgomery, a Democratic bastion and the state’s most populous county.

The backlash developing will embarrass O’Malley and his allies, at the least, and could potentially pose hurdles when they seek approval of the plan at a legislative session starting Oct. 17.

At least seven of nine members of the Montgomery County Council, all Democrats, plan to hold a news conference in Rockville on Tuesday to challenge the proposed map recently presented by O’Malley’s redistricting committee. State legislators representing minority communities, as well as a senior official of the state NAACP, will also attend.

Minorities are upset partly because the plan divvies up black, Asian and Latino voters in Montgomery to pack reliable Democrats into districts that almost certainly won’t be represented by minority legislators. In particular, up-and-comer Rep. Donna Edwards, who is black and whose district has included precincts in both Montgomery and Prince George’s, will lose all of her voters in Montgomery.

“A strong majority [of the council] is prepared tomorrow to come out against the proposed map, in favor of one that does not dilute the minority vote, that does not dilute communities of interest,” said Montgomery County Council President Valerie Ervin (D-Silver Spring), who is African American.

“The way this is drawn up, it will give us three white, male members of Congress,” she said. That referred to the prospect that Montgomery’s three representatives in the next Congress would be incumbent Democrats Chris Van Hollen and John Sarbanes, and either Republican Roscoe Bartlett or a white male Democrat who’d replace him.

Asked about the criticism, the governor’s office said the plan protects the African American majorities in two districts currently represented by blacks (Edwards and Elijah Cummings).

Also in O’Malley’s defense, he’s partly trying to do what he thinks is necessary to defend the Democratic Party nationwide. Both Republicans and Democrats use their power of redistricting to squeeze out seats for themselves.

Montgomery Council Member Phil Andrews said that wasn’t enough. “You should do the right thing, and this plan fails any reasonable test of being responsible and fair,” he said.