Having been stymied by Congress in previous attempts to tighten gun laws, Obama Tuesday unveiled a set of actions that would modestly broaden the definition of who qualifies as a gun dealer, streamline reporting of mental health issues for purposes of background checks, require better tracking of lost or stolen firearms and bolster enforcement of existing laws.

“The gun lobby may be holding Congress hostage right now, but they can’t hold America hostage,” Obama said at the White House, standing with a group of people who were victims of shootings or lost loved ones to gun violence. “Congress still needs to act. The folks in this room will not rest until they do.”

The initiative falls short of the broad changes in gun laws that Obama has called for in the past. But it drew criticism even before it was previewed by White House officials Monday night and may face challenges in court.

House Speaker Paul Ryan and other Republicans denounced the move as executive overreach, with the Wisconsin Republican saying the effort “will no doubt be challenged in the courts.”

“His words and actions amount to a form of intimidation that undermines liberty,” Ryan said in a statement, adding that Obama “has never respected the right to safe and legal gun ownership.”

Obama’s measures include tougher rules for those who currently sell firearms at gun shows and on the Internet without submitting buyers’ names for criminal background checks, and a warning to sellers that they face criminal prosecution if they try to skirt the law.

The administration proposes hiring hundreds of new workers to modernize the background check system and to handle the additional requests for checks. In addition, Obama is requesting $500 million for new mental health research and the Department of Health and Human Services is clarifying rules to remove some of the barriers to reporting a person’s mental health status to the background check information system.

Obama invoked the list of mass shootings that have taken place while he’s been in office. He wiped tears from his eyes as he recalled the shootings of 20 children and six educators at Sandy Hook Elementary School in Newtown, Connecticut.

“Every time I think about those kids, it gets me mad,” he said.

Potentially the most contentious piece of Obama’s executive actions is broadening the definition of a gun dealer. The plan targets small-scale gun sellers, who may conduct transactions from home, a gun show or via the Internet and aren’t required to hold a license or submit buyers’ names for federal background screening.

Obama said requiring criminal background checks of buyers at at gun stores isn’t an infringement on the Second Amendment right to bear arms, and expanding those checks “is not a plot to take away everyone’s guns.”

However, the expanded background checks wouldn’t have blocked the sales of weapons used in most recent mass shootings, including the December terrorist attack in San Bernardino, California, and the 2012 massacre at Sandy Hook. The firearms in those cases were purchased legally through conventional outlets.

Gun rights organizations gave the president’s actions a mixed response, saying they wanted to see how the government implemented the new executive actions.

The National Shooting Sports Foundation said that it supported the administration’s effort to beef up staffing for the FBI’s background check system, and agreed that the government should do more to get mental health records shared with the federal government.

But the administration’s new criteria for who must register as a licensed gun dealer “needs considerable clarification,” the group said in a statement. And the administration’s requirement that manufacturers report weapons lost in shipping are “misdirected” because the recipients of the weapons are in better position to know if guns arrived, the group said.

Gun control advocates argue that any constraints on access to weapons will reverberate throughout the murky gun market that has been booming as the threat of new restrictions has made news. According to the FBI, the agency’s National Instant Background Check System processed 23.1 million firearm background checks in 2015. That was 2.2 million more than the previous year, and an all-time record for the agency.

White House officials said the executive actions would have a tangible impact. Press secretary Josh Earnest said that over the past 15 years, an average of 1,300 guns reported as lost or stolen had been recovered annually at crime scenes. The steps to tighten reporting could help reduce that number. And, the White House said, additional mental health screenings could help prevent suicides that represent two-thirds of the nation’s 30,000 annual gun deaths.

Mark Niquette, Andrew Harris and Toluse Olorunnipa contributed.