WASHINGTON (AP) — Supporters of President Barack Obama's gun-control proposals are planning a methodical, state-by-state campaign to try to persuade key lawmakers that it's in their political interest to back his sweeping effort to crack down on firearms and ammunition sales and expand criminal background checks.

To succeed will require overturning two decades of conventional wisdom that gun control is bad politics.

The National Rifle Association is confident that argument won't sell. But with polls showing majorities supporting new gun laws a month after the Connecticut shooting deaths of 20 schoolchildren and six adults, gun-control activists say the political calculus has changed. Their goal in coming weeks is to convince lawmakers of that, too, and to counter the NRA's proven ability to mobilize voters against any proposals limiting access to guns.

The gun-control advocates are focused first on the Senate, which is expected to act before the House on Obama's gun proposals. How Senate Majority Leader Harry Reid, D-Nev., proceeds will depend in part on what he hears from a handful of Democrats in more conservative states where voters favor gun rights. These include some who are eyeing re-election fights in 2014, such as Mark Pryor of Arkansas, Mark Begich of Alaska and Max Baucus of Montana.

"We need to tell our members of Congress that they've got to stand up for sensible gun laws, and if they do that, we will stand up for them, and if they don't we will stand up for whoever runs against them," New York Mayor Michael Bloomberg told the U.S. Conference of Mayors Friday. "Because that's exactly what the NRA is trying to do."

Bloomberg's group, Mayors Against Illegal Guns, is among a coalition of some 50 labor unions, advocacy groups and others that have been meeting since before Christmas to plot strategy, in loose coordination with the White House, according to people involved.

Just hours after Obama rolled out his gun proposals on Wednesday, the group gathered at the headquarters of the National Education Association to game out their plans. As of Friday, voters' calls to Reid's office were running two-to-one against Obama's proposals, a Reid aide said.

Story continues

Never far from such Democrats' minds is what happened in 1994, when the party suffered widespread election losses after backing President Bill Clinton's crime bill featuring a ban on assault weapons. Clinton and others credited the NRA's campaigning with a big role in those Democrats' defeats. And when the assault weapons ban came up for congressional renewal in 2004, it failed.

The goal of gun-control supporters will be to convince Democrats like Pryor, Begich and Baucus through phone calls, appearances at town hall meetings, print and TV ads and other means that voters in their state will support them if they back Obama's plans.

One group involved, the Coalition to Stop Gun Violence, ran print ads in North Dakota newspapers criticizing newly elected Democratic Sen. Heidi Heitkamp after she expressed doubts about Obama's proposals.

Activists have also identified a few Senate Republicans they hope to sway, including Mark Kirk of Illinois and Susan Collins of Maine. In the House, they're focused on 35 to 40 Republicans in suburban areas or districts carried by Obama, where voters might be more supportive of gun-control measures.

"We have a million grass-roots supporters who have sent almost 200,000 emails to Congress, tens of thousands of phone calls and are ready to go to town hall meetings and camp out if they have to," said Mark Glaze, director of the mayors group. He said of lawmakers: "In the end I'm confident that enough of them will look past the NRA's $2,000 contribution and do what the public is demanding."

But the NRA, which claims some 4 million members, has already activated its base, issuing a fiery appeal this week in which Executive Vice President Wayne LaPierre warned backers: "It's about banning your guns, PERIOD! ... I warned you this day was coming and now it's here. This is the fight of the century."

As publicity spreads about Obama's proposals the NRA has been adding about 8,000 members a day, according to the group's president, David Keene. The NRA grades lawmakers on votes and has had apparent success in swaying congressional debates for years.

"We support the folks who've helped us in the past, and we remind them that we're also interested in what they do today and tomorrow," Keene said. "I'm convinced that once this thing gets debated the folks who've been with us in the past are probably going to be with us in the future."

Obama's call for an assault weapons ban is a particularly heavy lift, but backers are more optimistic about increased background checks, which were favored by 84 percent in an Associated Press-GfK poll this week.

Supporters hope those kinds of poll numbers will help move lawmakers to buck history and the NRA and vote in favor of gun-control bills.

"We definitely have our work cut out for us. The math's not with us right now in terms of the votes," said Andy Pelosi, president of Gun Free Kids. "It's going to be difficult, but I am optimistic. I think the tone in the country is much, much different, and you can't underestimate that."

___

Associated Press writer Ken Thomas contributed to this report.