Outcome uncertain, Senate to vote on background checks

The Senate set a long-awaited vote for Wednesday on a bipartisan plan for expanding background checks to more firearms buyers, with supporters facing a steeply uphill path to victory.

By scheduling the roll call, Senate leaders ensured a showdown over the cornerstone of an effort by gun control supporters to tighten firearms laws following December's killings of 20 students and six aides at an elementary school in Newtown, Conn.

The Senate planned to vote on eight other amendments as well to a Democratic gun control bill that expands background checks, tightens laws against gun trafficking and boosts school safety aid.

They included Democratic proposals to ban assault weapons and high-capacity ammunition clips, a Republican proposal requiring states to honor other states' permits allowing concealed weapons and a broad GOP substitute for the measure.

• Dems scramble for votes on gun background check proposal
• Giffords, Biden honor Tucson shooting victim

Senate Majority Leader Harry Reid, D-Nev., and Minority Leader Mitch McConnell, R-Ky., announced their agreement to proceed on the votes beginning at 4 p.m. ET; all amendments will require 60 votes for passage.

A Senate Democratic leadership aide tells CBS News that even if the compromise background check amendment sponsored by Sens. Joe Manchin, D-W.Va. and Pat Toomey, R-Pa., fails, which is looking very possible, they could come back later with a new amendment on background checks, but the way forward after most of these amendments likely fail tomorrow is unclear.

Senate gun control supporters struggled Tuesday to salvage their drive to expand background checks to more buyers, buoyed by a visit from wounded former Rep. Gabrielle Giffords but facing enough potential opponents to derail their endeavor unless they can figure out how to win more votes.

No. 2 Democratic leader Richard Durbin of Illinois, his party's chief vote counter, left a lunch of Democratic senators saying they would need support from nine or 10 Republicans - a tall order. Subjecting more firearms transactions to the background checks now is the main thrust of the gun control effort launched after December's killings of 20 schoolchildren and six adults in Newtown, Conn.

Attending Tuesday's Senate lunch was Giffords, the Arizona Democrat severely hurt in a 2011 mass shooting in Tucson, and her husband, retired astronaut Mark Kelly. The two, gun owners both, have started a political committee that backs candidates who favor gun restrictions.

"His message was, `We've been through this,'" Durbin said, describing Kelly's remarks to the lawmakers. "`We're ready to fight back to stand up for those who have the courage to vote for gun safety.'"

Giffords did not address the lawmakers.

In a blow to gun control advocates, Sen. Dean Heller, R-Nev., became the latest Republican to say he will oppose a bipartisan compromise broadening background checks.

"I believe that this legislation could lead to the creation of a national gun registry and puts additional burdens on law-abiding citizens," he said.

Before the lunch, Giffords and Kelly met privately with Manchin and Toomey, R-Pa.

"They're helping immensely just by being here and talking to our colleagues. We're close, but we sure need their help," Manchin said after that meeting.

The two senators' effort is aimed at weeding out criminals and the seriously mentally ill from getting firearms. The current background check system applies only to transactions with licensed gun dealers.

Though the Senate has been debating a broader gun bill for days, it remained unclear when votes on the Manchin-Toomey plan or other amendments would begin. Democrats were hoping roll calls could start as early as Wednesday, with the two senators' proposal generally seen as the first vote.

President Obama, in an interview with NBC's "Today" show, urged lawmakers to pay attention to public support for expanding background checks and remember the massacre at Sandy Hook Elementary School.

"The notion that Congress would defy the overwhelming instinct of the American people after what we saw happen in Newtown, I think is unimaginable," Obama said in the interview, aired Tuesday.

National Rifle Association spokesman Andrew Arulanandam said the organization was spending $500,000 on an online video ad on conservative and Washington-area websites that cites a survey from a police-oriented website showing opposition to gun control proposals. "Tell your senator to listen to America's police, instead of listening to Obama and Bloomberg," said the ad, referring to gun control advocate Michael Bloomberg, New York City mayor.

Besides the Manchin-Toomey proposal, Democrats were ready to offer other amendments - likely to lose - banning military-style assault weapons and ammunition magazines capable of carrying more than 10 rounds. Authorities have said both were used in the Newtown rampage.

Sen. John Cornyn of Texas, the No. 2 Senate GOP leader, said he was working on an amendment requiring states to recognize each other's permits for carrying concealed weapons.

While all states but Illinois, plus the District of Columbia, issue permits or have other arrangements for permitting concealed weapons, nine states don't recognize permits from other states. Gun rights defenders say making it easier to move firearms between states is protected by the Constitution, while opponents complain it would hurt states that have stricter standards for permits than others.

"Hopefully we'll start voting on this. I don't know of any reason why we wouldn't," Cornyn told reporters.

Using procedural moves, opponents would 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 vote against the Manchin-Toomey measure - which 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 is 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.

As of Tuesday afternoon, Manchin, Toomey and their allies were still hunting supporters.

"We're working to get 60, and it's fluid," Vice President Joe Biden told reporters, citing the number of votes his side would need to prevail.

Aides and lobbyists have said the two lawmakers are considering allowing changes in their bill to exempt people who live far from gun dealers, making it difficult to go to the dealers' shops to have background checks performed. The hope was to attract votes from Alaska and North Dakota.

In addition, Democrats were considering allowing other votes to come before the vote on Manchin-Toomey. That might make it easier to win support for the background check expansion by letting some senators vote first against other proposals, such as the assault weapons ban, to show voters they support gun rights.

Sen. Chuck Schumer, D-N.Y., the third-ranking Senate Democratic leader, was among several in his party who cited emotional speeches by other senators in their lunch Tuesday as giving hope to supporters of expanded checks.

He also emphasized the help gun control advocates have received from families of victims of Newtown and other mass shootings who have spent many recent days visiting senators.

"The more the families who were here again have a chance to talk to people, the better we do. So if it's possible I'd like to get a little more time," Schumer said.

CBS News' Jill Jackson contributed to this report