"They have made clear that they're in this for the long haul and they want us to be in this for the long haul," said Dan Gross, president of the Brady Campaign to Prevent Gun Violence.
Advocates participating in Wednesday's meeting, some of whom have been critical of Obama's silence on guns in the past, said they were optimistic that the president and Biden are committed to the effort this time around.
"I think it's for real," said Shira Goodman, executive director of CeaseFirePA.
Biden also held a call with Wednesday with more than 30 governors, mayors and other state and local officials to get their input on ways to curb gun violence.
For Biden, Thursday will bring a tougher audience when the NRA joins a meeting at the White House along with other gun-owner groups and retailers including Wal-Mart. NRA officials didn't return messages for comment Wednesday but the group's executive vice president, Wayne LaPierre, has dismissed the assault weapons ban as "a phony piece of legislation" and has recommended putting armed guards in all schools as a way to stop another school shooting.
Biden said he wanted to hear from "all parties, on whatever side of this debate you fall."
The president hopes to announce his administration's next steps to tackle gun violence shortly after he is sworn in for a second term on Jan. 21.
Associated Press writers Darlene Superville and Julie Pace contributed to this report.
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