PHOENIX — More than 500 leaders of a national network of young immigrants, frustrated that House Republicans said they would not move on immigration this year, have decided to turn their protests on President Obama in an effort to pressure him to act unilaterally to stop deportations.

After months of lobbying, rallies and sit-in demonstrations ended with no movement in the House on a pathway to citizenship for immigrants here illegally, the youths who gathered in Phoenix this weekend for an annual congress of the network, United We Dream, said they felt disappointed by Republicans and Democrats. Pointing to Mr. Obama’s pledge early this year to use his phone and pen when Congress did not move on his agenda, they said they would demand that he take executive action to increase protections for immigrants without papers.

“The community we work with is telling us that these deportations are ripping our families apart; this has to stop,” said Cristina Jiménez, the managing director of the network, the largest organization of immigrants who grew up in this country without legal status after coming as children and who call themselves Dreamers. “And we know the president has the power to do it.”

The young immigrants’ demands will be uncomfortable for Mr. Obama in a midterm election year when his low approval ratings could allow Republicans to make important gains. Polls show wider sympathy among Americans for young immigrants than for others without legal status, and the young people have often been leaders in setting strategy among immigrant groups.