LAS VEGAS (AP) — Mounting an offensive behind his immigration directives, President Barack Obama on Friday insisted House Republicans must take up a comprehensive immigration overhaul but said the system is so unfair that it needs the type of fixes that he initiated on his own.

"Our immigration system has been broken for a very long time and everybody knows it," he said. "We can't afford it anymore."

Speaking at the Las Vegas high school where he launched his drive for Congress to send him an immigration bill, Obama outlined steps he has taken to help millions of people living in the country illegally. The measures are designed to make nearly 5 million of those immigrants eligible for protection from deportation and for work permits.

But Obama cautioned that his actions are limited and that only broader legislation would permanently change immigration laws and help the more than 11 million immigrants illegally in the United States.

"The actions I've taken are only a temporary first step," he said.

As if to underscore that point, a heckler interrupted Obama, chiding him for not doing enough with his executive actions to help more immigrants in the country.

"Not everyone will qualify," Obama conceded. "That's the truth. Listen, I heard you and what I'm saying is we're still going to have to pass a bill."

With Republicans accusing him of overstepping his authority, Obama and his allies are seeking to sell the executive actions on immigration as good politics and good policy. But he also sought to use his move to apply pressure on Republicans, who seemed to be casting about for a way to respond without overplaying their hand.

The actions, which Obama laid out in a prime-time television address Thursday, would mainly cover parents of U.S. citizens and of legal residents as long as the parents have been in the U.S. for five years or more. But Obama's actions also would change enforcement priorities by emphasizing the deportation of new illegal arrivals and criminals.

House Speaker John Boehner, R-Ohio, said Obama, in sidestepping Congress, had damaged his ability to get things done.

"In the days ahead the people's house will rise to this challenge" Boehner said Friday at the Capitol. "We will not stand idle as the president undermines the rule of law in our country and places lives at risk. ... He's damaging the presidency itself."

But Obama countered that it has been Republicans who have stood in the way, noting that 512 days have passed since the Senate passed a comprehensive bill.

"The fact that a year and a half has gone by means that time has been wasted and during that time families have been separated and during that time businesses have been harmed," he said, promising to keep working with lawmakers to achieve a comprehensive bill.

"So Las Vegas, I've come back to Del Sol to tell you I'm not giving up. I will never give up."