President Joe Biden will unveil measures on Thursday aimed at curbing rampant US gun violence, especially seeking to prevent the spread of untraceable “ghost guns,” White House officials said. Biden has come under pressure from his Democratic party to tackle the bloodshed, most recently highlighted by mass killings in Colorado, Georgia and California.In addition to relatively modest measures on the politically hyper-sensitive issue, Biden will announce his nomination of David Chipman, a gun-control proponent, to head the Bureau of Alcohol, Tobacco, Firearms and Explosives — a central agency in the fight against gun violence.Reflecting the lack of political unity around anything to do with firearms restrictions, the ATF has not had a Senate-confirmed director since 2015.Chipman is a veteran of the agency who went on to work for a gun control advocacy group and there is no one “better to enforce gun laws,” a senior administration official said.The official, who spoke on condition of anonymity, said Biden would be issuing six measures “to address the gun-violence health epidemic.”Standing out is a proposed new rule to “stop proliferation of ghost guns,” as firearms built from home kits are known. The official said these homemade weapons are especially of concern because when found at crime scenes “they cannot be traced.”Other measures include boosting support for agencies involved in tackling community violence and ordering the first comprehensive report on firearms trafficking in the United States since 2000.Absent, however, will be any big measures on seeking to tighten overall gun laws, such as more background checks or ending the sale of powerful rifles often used in mass killings.The official stressed that Thursday’s measures — where Biden is reportedly due to be accompanied by Attorney General Merrick Garland — are only “initial” steps.Biden has long promised to get tough on a US gun culture that he says fuels an epidemic of mass shootings, as well as the even more deadly, yet less reported, daily stream of gun crimes and suicides.The Democrat says he supports tighter background checks for firearms buyers and a ban on military-style rifles dubbed assault weapons. Both ideas face strong resistance in Congress.Biden successfully backed an assault weapons ban in 1994 when he was a senator. The law expired a decade later, however, and has never been renewed, with Republicans increasingly rigid in opposing what they depict as an attack on the constitutional right to bear arms.