By ALAN FRAM
WASHINGTON (AP) -- A bipartisan effort to expand background checks is in deep trouble as the Senate approaches a long-awaited vote on the linchpin of the drive to curb gun violence. As the showdown draws near, an Associated Press-GfK poll shows ebbing public support for tightening gun control laws.
In the run-up to the roll call expected Wednesday, so many Republicans had declared their opposition to the background check measure that supporters -- mostly Democrats -- seemed headed to defeat unless they could turn votes around in the final hours. Supporters seemed likely to lose some moderate Democratic senators as well.
"It's a struggle," New York Sen. Chuck Schumer, the No. 3 Senate Democrat, conceded Tuesday.
Perhaps helping explain Democrats' problems, an AP-GfK poll this month showed that 49 percent of Americans support stricter gun laws. That was down from 58 percent who said so in January -- a month after the December killings of 20 children and six aides at a Newtown, Conn., elementary school propelled gun violence into a national issue.
Just over half the public -- 52 percent -- expressed disapproval in the new survey of how President Barack Obama has handled gun laws. Weeks after the Newtown slayings, Obama made a call for near universal background checks the heart of his gun control plan.
"Every once and awhile we are confronted with an issue that should transcend politics," Obama said in an interview that aired Wednesday on NBC's "Today" show. "And now's the time for us to take some measure of action that's going to prevent some of these tragedies from happening again."
In a climactic day, the Senate planned to hold eight other votes Wednesday besides the one on background checks, all of them amendments to a broad gun control measure.
They included Democratic proposals to ban assault weapons and high-capacity ammunition magazines, which are expected to lose; a Republican proposal requiring states to honor other states' permits allowing concealed weapons, which faces a close vote; and a GOP substitute for the overall gun measure.
The concealed weapons amendment, seen by advocates as protecting gun rights, was vehemently opposed by gun control groups, who say it would allow more guns into states with stricter firearms laws.
The votes were coming a day after former Rep. Gabrielle Giffords, badly injured in a 2011 mass shooting in Tucson, Ariz., and her husband, Mark Kelly, tried galvanizing gun control support by visiting Capitol Hill and attending a private lunch with Democratic senators. Senate Majority Leader Harry Reid, D-Nev., called the lunch -- senators said it included emotional speeches from lawmakers -- "as moving as any" he has attended.
Background checks, aimed at screening out criminals and the seriously mentally ill from getting firearms, now apply only to purchases handled by licensed firearms dealers.
Wednesday's first vote was on an amendment by Sens. Joe Manchin, D-W.Va., and Patrick Toomey, R-Pa., extending the checks to firearms sales at gun shows and online. The compromise was widely seen as advocates' best chance for winning enough GOP votes to muscle broadened checks through the Senate.
As the roll call approached, Manchin and others kept saying they were close -- but never said they had the votes they needed.
"We're close, but we sure need their help," Manchin told reporters after he and Toomey met privately with Giffords and Kelly.
In a sign that the two senators faced a steep path to victory, they were no longer considering a change to their bill that would have exempted people who live far from gun dealers.
Such people have a difficult time getting to dealers' shops to have background checks performed. The hope had been to attract votes from Alaska and North Dakota senators, and the sponsors' decision to move ahead without it suggested that their effort to win over those senators would fail.
No. 2 Senate Democratic leader Dick Durbin of Illinois said Democrats would need support from nine or 10 Republicans -- a daunting task.
Opponents will need just 41 of the Senate's 100 votes to derail the Manchin-Toomey background check plan.
Thirty-one senators voted last week to completely block debate on overall gun legislation. Just two were Democrats -- Mark Pryor of Arkansas and Mark Begich of Alaska.
If all 31 oppose the Manchin-Toomey measure -- and that is not certain -- opponents would need just 10 more votes to prevail.
So far, 11 of 16 Republicans who voted last week to let debate on the gun bill begin have said they will oppose Manchin-Toomey. That would give foes of expanded background checks 42 potential votes -- one more than they need to win.
Still uncertain was support from some Democrats from GOP-heavy states, including Max Baucus of Montana, Mary Landrieu of Louisiana and Heidi Heitkamp of North Dakota. Baucus and Landrieu face re-election next year.
The Senate gun bill would extend background checks to nearly all gun purchases, toughen penalties against illegal gun trafficking and add small sums to school safety programs.
The AP-GfK poll found that overall, 49 percent said gun laws should be made stricter while 38 percent said they should stay the same.
Among independents, support for stricter gun laws dipped from 60 percent in January to 40 percent now. About three-fourths of Democrats supported them then and now, while backing among Republicans for looser laws about doubled to 19 percent.
The AP-GfK poll was conducted from April 11-15 by GfK Roper Public Affairs and Corporate Communications. It involved landline and cellphone interviews with 1,004 randomly chosen adults and had a margin of sampling error of plus or minus 3.9 percentage points.
AP Director of Polling Jennifer Agiesta, news survey specialist Dennis Junius and writers Henry C. Jackson, Stephen Ohlemacher and Jim Abrams contributed to this report.