In an interview Tuesday, Burbank said the strong language of the letter was approved by the association's five-member board of directors but that the association's support of stronger gun laws which include universal background checks, limits to high-capacity magazines and a ban on assault weapons represents the unanimous opinion of the association's members, who oversee police agencies in the 70 largest cities in the U.S. and Canada. Burbank has been the board's vice president for three years.
Burbank said that while mass shootings such as the ones in Aurora, Colo., and Newtown, Conn., get the most attention, there are many other gun deaths in cities across the country that police deal with every day. Restricting criminals' access to guns would make a difference, he said.
"People who want to do society harm are getting access to firearms when they shouldn't," Burbank said.
Burbank said that the measures supported by the police chiefs were moderate.
"Reasonable, in the middle, is where we need to be, and unfortunately there doesn't seem to be a lot of reason in this current debate," he said.
The letter also cited last week's bombing attacks by two suspects in Boston, which also included the fatal shooting of a police officer, as "a reminder of the violence that constantly threatens the public and their police."
"Like all cops who put on a uniform each day, Chiefs of Police will not give up on Washington," the statement continues. "We will continue our struggle for laws that protect the public from gun violence."
In addition to the background checks amendment, both Republican Utah Sens. Orrin Hatch and Mike Lee opposed an amendment to limit the size of gun magazines and enact a ban on assault weapons.
The Utah senators did vote in favor of a Republican amendment that would increase resources for gun prosecutions, augment mental health screenings and add to school security, as well as permit interstate handgun sales. None of the amendments met the chamber's 60-vote threshold to pass.
"[Senator Hatch] voted for a proposal that wouldn't restrict Second Amendment rights," said Hatch spokesman Matthew Harakal on Tuesday.
Harakal noted that Burbank did not reach out to the senator's office before the vote. The day after the measures failed, Hatch said in a Senate floor speech that the measures he voted against "failed to respond to the Newtown tragedy."
Hatch added that "people, not guns, kill and harm other people and criminals will not obey the law."
"It does no good to pretend otherwise or legislate for a society in which those things are not true, in other words, for a society that does not exist," Hatch said.
Lee's office declined on Tuesday to offer any comment on the police chiefs' statement, but Lee has offered previous public statements about his vote.
In an op-ed piece published in USA Today on the day the gun measures were defeated, Lee defended his decision to vote against the background checks measure, known as the Toomey-Manchin amendment, saying it was "too vague for law-abiding citizens to understand with certainty, and too easy for criminals to avoid."
"Gun-control advocates point to polls that show support for expanding background checks," Lee wrote, "But members of Congress do not get to vote on broad poll questions. They have to vote on specific legislation. If we are trying to minimize the burden on law-abiding gun owners while taking significant steps to prevent the next Sandy Hook, the Toomey-Manchin amendment, and the others that would have limited Second Amendment rights, failed both elements of that test."