Gun control activists are readying a major district-by-district effort in the hope of pushing parts of President Barack Obama’s plan to address gun violence through Congress.

Just hours after Obama called on lawmakers to pass a series of measures, an alliance of liberal groups, unions and gun control activists gathered at the Washington headquarters of the National Education Association to develop a path to 218 votes in the Republican-controlled House.

The activists plan to focus on more than a dozen House Republicans from districts Obama won last year, including members from New York, Florida, Pennsylvania and Michigan, according to documents provided to CQ Roll Call by a source involved in the planning. The campaign will likely include Capitol Hill lobbying, in-district events and paid advertising.

“The math is not with us right now, so the ground game is going to be the difference,” said Andy Pelosi, president of Gun Free Kids, who is working with the coalition. “We will have a ground game like never before.”

Obama called on Congress on Wednesday to renew and strengthen a federal ban on military-style assault weapons that expired in 2004, limit ammunition magazines to 10 rounds and require criminal background checks on all gun sales. He also requested more serious penalties for gun trafficking and a ban the sale or possession of armor-piercing bullets. All of the proposals face an uphill battle.

The background check proposal, which is intended to bar criminals and the mentally disabled from buying guns, is seen as the most likely point of compromise. Today, only licensed dealers, who conduct only 60 percent of all gun sales, are required to conduct criminal background checks. Gun control activists hope to pick up the support of licensed gun dealers, who lose business to private sales.

Some of the groups at Wednesday’s strategy session, convened by Americans United for Change, plan to invest heavily in paid radio and television ads, said Robert Creamer, a consultant for the liberal group. Representatives from the American Bar Association, Service Employees International Union and dozens of other groups attended the meeting, he said.

“There will be a bunch of them who are gathering their resources to play heavily in the next election,” he added. “The public relations war is over; what we are going to see now is the political war beginning.”

Indeed, several targeted lawmakers including Reps. Dave Reichert, R-Wash., a former sheriff, Patrick Meehan, R-Pa., a former U.S. attorney, and Rep. Jon Runyan, R-N.J., could could swing in support of the measures, if they come up for a vote.

“We will be doing polling in a lot of districts, and we will be giving our mayors and grass-roots survivors something to do everyday,” said Mark Glaze, a lobbyist at the Raben Group, who represents Mayors Against Illegal Guns, a well-funded bipartisan group led by New York Mayor Michael Bloomberg.

The progressive phone company Credo Mobile is urging activists to call their senators and ask them where they stand on banning assault weapons and high-capacity ammunition clips.

But the challenge for the coalition will be coordinating and directing the energy and resources of a wide swath of liberal groups toward achievable goals. Renewal of the assault weapons ban, in particular, faces long odds in the current Congress, activists said.