Mayor Michael Bloomberg's gun control group is launching another ad campaign ahead of Congress' debate on gun legislation.
Mayors Against Illegal Guns is airing a TV spot in Washington D.C. and seven states, asking viewers to urge their senators to support the measure.
Debate is expected to begin Tuesday.
Meanwhile, President Barack Obama turned to a parent of one of the Connecticut school shooting victims to make his case for gun control.
Francine Wheeler, the mother of 6-year-old Ben Wheeler, made a personal plea Saturday in the president's weekly address.
Wheeler said the young lives taken in that massacre, as well as the thousands of other American lives cut short by gun violence in the months since, are proof that Congress has to act to curtail the availability of firearms.
"We have to convince the Senate to come together and pass common sense gun responsibility reforms that will make our communities safer and prevent more tragedies like the one we never thought would happen to us," she said.
It was the first time someone other than President Obama or Vice President Joe Biden gave the address since the two took office.
A bipartisan agreement was reached by two senators earlier this week.
It would require federal background checks for weapons sold at gun shows and online.