President Obama on Monday responded to critics from the Left who have urged him to issue more executive orders to bypass legislative opposition on key issues, arguing that he could not “nullify Congress."

During a fundraiser for the Democratic National Committee in San Francisco, Obama was heckled by an audience member who repeatedly shouted “executive order” during the president’s remarks.

“Somebody keeps on yelling, ‘executive order,’ ” said Obama, responding to the heckler. “I’m going to actually pause on this issue because a lot of people have been saying this lately on every problem, which is just, ‘Sign an executive order and we can pretty much do anything and basically nullify Congress.’

“That’s not how it works,” he continued. “We’ve got this Constitution, we’ve got this whole thing about separation of powers. So there is no shortcut to politics, and there’s no shortcut to democracy."

Obama said that Democrats needed to make their case to the public and win support on important issues.

“We have to win on the merits of the argument with the American people, as laborious as it seems sometimes,” said Obama. “What we have to do is keep on going, keep on pushing, and eventually we move in a better direction.”

The president has faced pressure from liberal groups to use executive orders to enact key immigration reforms and to prevent discrimination in the workplace against gays and lesbians.

Efforts to overhaul the nation’s immigration laws and pass the Employment Non-Discrimination Act have both stalled in the GOP-controlled House.

Earlier Monday, Obama was also heckled by an immigration reform advocate during an address in San Francisco. The heckler urged Obama to do more to stop deportations of illegal immigrants already in the country.

“The easy way out is to try to yell and pretend like I can do something by violating our laws,” said Obama in response. “It won’t be as easy as just shouting.”

The president has already enacted a number of executive orders, issuing a measure ordering the closure of Guantanamo Bay as one of his first acts in office. Obama’s push to shutter the military prison housing terror suspects, though, met with opposition from Congress.

Obama has also issued executive orders halting the deportation of some young illegal immigrants and tightening federal gun laws in the aftermath of the Sandy Hook Elementary School shooting.