U.S. Attorney General Eric Holder, speaking to the U.S. Conference of Mayors Friday in Washington, called on mayors to push for “immediate congressional action” that would force gun-show and private gun sellers to fully check the backgrounds of all their customers. (JONATHAN ERNST/REUTERS)

Attorney General Eric H. Holder Jr. urged the nation’s mayors Friday to support President Obama’s plan to require a background check for everyone who buys a firearm in the United States.

In his most extensive remarks about gun control, Holder called on mayors to push for “immediate congressional action” that would force gun-show and private gun sellers to fully check the backgrounds of all their customers.

“By taking this relatively simple step, we can significantly strengthen our ability to keep criminals and other dangerous individuals from getting access to deadly weapons,” Holder told a committee at the U.S. Conference of Mayors meeting in Washington. Until Congress takes action, he urged the mayors to encourage private gun sellers to run their transactions through the FBI background system with the help of a licensed firearm dealer.

Addressing the fuller Obama package, Holder said: “Some have said that these changes will require tough votes by members of Congress. As you all know, public service is never easy, and there come times when those of us who are elected or appointed to positions must put the interests of those who we are privileged to serve above that which might be politically expedient or professionally safe.”

Administration officials said privately that, among the major legislative items in the president’s proposals, the “universal” background check is the most likely to win bipartisan support in Congress. A ban on military assault weapons and high-capacity magazines is expected to face strong opposition from the gun lobby, said congressional and administration officials, who asked that their names be withheld because they were not authorized to speak to the press.

President Obama proposed expansive gun-control policies aimed at curbing gun violence. The Obama administration can implement about half of the proposals, but the others — arguably some of the more critical initiatives — will require congressional approval.

Addressing another element in Obama’s program, Holder called for the Senate to confirm B. Todd Jones as director of the Bureau of Alcohol, Tobacco, Firearms and Explosives. The agency, which regulates firearms and investigates gun violence and illegal gun trafficking, has been without a director for six years, largely due to efforts by the gun lobby to block previous nominees.

In signs of potential trouble for Obama’s new nominee, Republican lawmakers criticized Jones for his involvement in issues related to Fast and Furious, the ATF’s botched gun operation in Phoenix.

Jones, who is interim acting director of the AFT while also serving as U.S. attorney in Minnesota, volunteered to head the agency amid a leadership vacuum after the previous acting director resigned during the congressional investigation of Fast and Furious.

“Acting Director Jones was at the helm of the ATF as many troubling problems from the fallout of Operation Fast and Furious festered,” Rep. Darrell Issa (R-Calif.), chairman of the House Oversight and Government Reform Committee, said in a statement. “His specific decisions on a number of Fast and Furious related issues raise concerns about his judgment and ability to lead the agency.

“While I continue to believe that ATF needs to have a Senate confirmed Director, President Obama has a responsibility to find a nominee who can win confirmation and is not saddled by a string of bad decisions related to the agency’s greatest recent failure,” Issa said.

Sen. Charles E. Grassley (R-Iowa) said he, too, has questions about Jones’s decisions related to Fast and Furious and a Minnesota legal case involving housing discrimination.

Grassley and other lawmakers said that they did not try to block Obama’s first nominee to head the ATF, Andrew Traver. They say that after Obama nominated Traver, neither the White House nor Democrats in Congress did anything to to move the nomination forward.

In addition to Holder, the mayors’ conference also drew another gun-control advocate, New York Mayor Michael Bloomberg. He backed Holder’s push for universal background checks.

“Background checks for all gun sales will dramatically reduce the illegal traffic that leads to murder,” Bloomberg said. “It will dramatically reduce domestic violence. It will dramatically reduce suicides. It’s a law that works, and we’ve got to tell our members of Congress that it is time to make it the law of the land.”

Vice President Biden delivered a point-by-point defense of the White House gun agenda Thursday in a luncheon address at the mayoral summit. Obama on Wednesday unveiled the 23-point plan to curtail gun violence.

The White House proposal calls for the implementation of universal background checks, a crackdown on gun trafficking, the passage of an assault weapons ban and a ban on high-capacity magazines.