The problem in getting the legislative part of the president's gun program - most notably, a renewed and stronger ban on assault rifles - through a divided Congress was driven home by a testy war of words Wednesday between Mayor Nutter, who was in D.C. for a legislative gun hearing, and Florida Sen. Marco Rubio, a GOP rising star.
Rubio said in a statement that "President Obama's frustration with our republic and the way it works doesn't give him license to ignore the Constitution."
In response, Nutter told reporters from The Hill newspaper: "If the gentleman just wants to be opposed just because he wants to be opposed, I generally don't argue with people who engage in that kind of irresponsible behavior."
So what's all the shouting about?
* Obama signed 23 executive orders that don't require the backing of lawmakers - ordering federal agencies to make more data available for background checks, appointing a director of the Bureau of Alcohol, Tobacco, Firearms and Explosives, and directing the Centers for Disease Control and Prevention to research gun violence.
* He called for improvements in school safety, including putting 1,000 police officers in schools and bolstering mental-health care by training more health professionals to deal with young people who may be at risk - all part of a $500 million program.
* He proposed more ambitious measures that will need the OK of Congress - highly uncertain in the current climate - including universal background checks and bans on military-style assault weapons and high-capacity ammunition magazines like the ones used in the Newtown, Conn., school shooting.
"Gun-control advocates are ecstatic today," Adam Winkler, UCLA law professor and author of Gunfight: The Battle over the Right to Bear Arms in America, said in a phone interview. He said that those wanting tougher gun restrictions have been waiting nearly two decades for such an announcement. "In [Obama's] last term, you would mention the word 'gun' and he would hide under the table."
Validating Winkler's remark was a pleased Shira Goodman, executive director of the anti-gun-violence group CeasefirePA, who said that proposals such as tighter background checks "make a whole lot of sense to a lot of people." She said that her only small regret was that there weren't more incentives for states such as Pennsylvania to address a huge lag in entering mental-health records into the federal database.
Not so delighted were callers to local talk radio, who tend to be more conservative. Host Dom Giordano, of WPHT (1210-AM), said in an email that "I really don't like the President using four kids as props on this." He added: "I don't like the 23 executive orders. I'm not going to act irresponsibly and call it the end of our liberty."
On Twitter: @Will_Bunch