WASHINGTON — Gun control forces are targeting Sens. Kelly Ayotte, Max Baucus and others as they struggle to persuade five senators to switch their votes and revive the rejected effort to expand background checks to more firearms buyers.

With Congress back from a weeklong recess, the bottom line remains familiar: Advocates of broadened checks lack the new votes they need and Congress has moved on to other issues. A few lawmakers who opposed expanding the checks when the Senate defeated the measure last month say they'd consider changes the sponsors might offer but haven't committed to backing anything, while others show no signs of switching.

"I stand by my vote," one prime target, Ayotte, R-N.H., said Monday.

A new vote seems unlikely until at least early summer.

As time passes since the December slayings of 20 first-graders and six educators at a Newtown, Conn., elementary school, supporters of firearms restrictions say they won't let public and congressional fervor fade, as it has after previous mass shootings. They're launching fresh activities, such as a "Mother's Day Week of Action" by the Brady Campaign to Prevent Gun Violence and other groups, aimed at convincing lawmakers that continued opposition would be politically perilous.

"We have all the time in the world, except that 33 more Americans are being murdered every day," said Mark Glaze, director of Mayors Against Illegal Guns, citing the approximate average of daily gun homicides. Led by wealthy New York Mayor Michael Bloomberg, the gun control group unveiled a new TV ad Monday aimed at Ayotte, and Glaze said the group will hold events in targeted states "every time senators are home on vacation."

Others say the passage of time is no help to supporters of firearms restrictions.

"If they don't get something now, when are they going to win?" said Harry Wilson, a political science professor at Roanoke College in Salem, Va., who has written a book on gun control politics. "The further away you get from the event, every day your chances diminish a little."

Lawmakers who voted "no" but whom gun control advocates hope to change include Ayotte and Baucus, D-Mont., plus Sens. Mark Begich, D-Alaska; Jeff Flake, R-Ariz.; Heidi Heitkamp, D-N.D.; Dean Heller, R-Nev.; Lisa Murkowski, R-Alaska; and Mark Pryor, D-Ark.

Senate Majority Leader Harry Reid, D-Nev., told the Las Vegas Review-Journal last week that a chief sponsor of the background check expansion, Sen. Joe Manchin, "thinks he has a couple more votes."

Manchin said Monday that "nothing's changed," though he said he has had "some real good discussions." The other chief author, Sen. Patrick Toomey, R-Pa., said he talked to other senators during the recess but added, "I can't say that I did" win over any of them.

On Tuesday, Manchin said in a broadcast interview that he had no intention of abandoning the fight.

The West Virginia Democrat told "CBS This Morning" that adjustments and revisions are necessary to find "where the comfort zone is" with gun owners. But he also asserted that the National Rifle Association, of which he is a member, has been "rattling the cage" to rally opposition to any expansion of background checks.

Gun control supporters must persuade at least five senators who've already voted no to vote yes – never an easy task. That could require building a public outcry that convinces senators their constituents think they voted the wrong way, then revamping the bill so senators can say they forced changes they can now support.

Tactics being used include:

_ TV ads last week by the liberal Progressive Change Campaign Committee targeting Baucus, in which a Montana grandmother and home invasion victim says, "We're less safe with guns in the wrong hands."

_ Gun victims' relatives invited senators to dinner in their homes to see the empty seat once occupied by the slain family member. Sandy Phillips, 63, of San Antonio, whose daughter was killed in the 2012 mass shooting in an Aurora, Colo., movie theater, said she met in a restaurant with conservative Sen. Ted Cruz, R-Texas, but failed to persuade him to support expanded checks.

_ The Brady campaign and other groups were using the approach of Mother's Day this Sunday to urge mothers and others to contact lawmakers using social media, letters to the editor and phone calls to legislators' offices.

_ Vice President Joe Biden met Monday with members of religious organizations that favor gun control, urging them to continue the fight and saying the Senate could reconsider the issue after it finishes immigration legislation, which likely won't be until at least June. Last week he met with law enforcement groups.

The NRA used its annual convention in Houston this weekend to urge supporters to "regain the political high ground" by focusing on next year's congressional elections. New NRA President James Porter told the gathering, "We do that and (President Barack) Obama can be stopped."

Pryor said Monday that if sponsors change the bill he'll "look at whatever," but said he's received "lots of positive feedback" from voters and said a Republican alternative he supported that stressed stronger enforcement of current laws was better.

In an interview last week, Flake said the rejected bill's definition of commercial sales was too broad, saying it could cover someone who uses email to sell firearms to a friend.

Asked whether he could support a measure with a narrower definition of commercial sales, he said he wanted to strengthen the law's mental health restrictions. "I'll look at it, I'll work with the sponsors to try to get something where we can strengthen background checks without infringing on the Second Amendment rights of law-abiding citizens," Flake said.

Gun control groups have targeted Flake because fellow Arizona GOP Sen. John McCain backed the legislation and because Arizona is the home state of wounded former Rep. Gabrielle Giffords, now an active gun control advocate.

Ayotte, whose "no" vote dashed gun control forces' hopes, has been a focal point of their pressure. The mayors' group planned to air a TV ad this week accusing her of having "gone Washington" by opposing the background check expansion, despite the proposal's backing by huge majorities in public opinion polls.

She gained national attention when she was confronted at a town hall meeting last week and asked to explain her vote against the background check measure by Erica Lafferty, daughter of Dawn Hochsprung, the slain principal of Newtown's Sandy Hook Elementary School.

The defeated legislation would require background checks for advertised sales, including at gun shows and on the Internet. Non-commercial transactions like those between people who know each other would be exempt.

Background checks, designed to keep criminals and the mentally ill from getting firearms, currently apply only to sales through licensed gun dealers.

___

Associated Press writer Andrew Miga contributed to this report.

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