"We define ourselves as a nation of immigrants -- a nation that welcomes those willing to embrace America's precepts," Obama said during a visit to El Paso, Texas.
"It doesn't matter where you come from. What matters is that you believe in the ideals on which we were founded, that you believe all of us are equal," he said. "In embracing America, you can become American. That is what makes this country great."
The president's speech was part of his administration's attempt to regain the initiative on a hot-button issue that has largely been ceded to state government leaders in recent months. It took place against a backdrop of intense political maneuvering on the part of both Democrats and Republicans seeking to use the issue to their own advantage in the 2012 election campaign.
Immigration reform advocates urge Obama to take action
Obama's speech came in the wake of a series of recent meetings with key Latino officials and reform advocates. Despite an aggressive push for substantive policy changes from his political base, the president has repeatedly said he won't act on his own to implement provisions of a reform bill that failed to win congressional approval last year.
Some reform advocates "wish that I could just bypass Congress and change the law myself. But that's not how a democracy works," the president said.
The president has, however, changed Washington's enforcement priorities.
A recent increase in deportations "has been a source of controversy," he acknowledged. "But I want to emphasize: We are not doing this haphazardly. We are focusing our limited resources on violent offenders and people convicted of crimes -- not families, not folks who are just looking to scrape together an income."
A number of states -- most notably Arizona -- are moving in the opposite direction, pushing legislation making it easier to deport people solely for being in the country illegally.
Key parts of a new Arizona law requiring police officers to check a person's immigration status while enforcing other statutes were recently blocked by the federal courts. The Justice Department sued the state, arguing that only the federal government has the authority to dictate immigration policy.
Federal district and appellate judges have blocked that provision of the law, and Arizona's governor asked the U.S. Supreme Court to take the case Monday.
For their part, national Republican leaders have indicated an unwillingness to consider broader changes -- including a path to citizenship for undocumented immigrants -- until the Mexican border is brought under tighter control.
Progressive reform advocates, meanwhile, have been frustrated by Congress's inability to pass the DREAM Act, which would offer legal standing to immigrants who entered the United States illegally as children under the age of 16 and have lived in the country for at least five years.
The bill would require, among other things, a high school or General Educational Development diploma, two years of college or military service, and criminal background checks.
Advocates say the bill would give legal standing to young people brought to the United States by their parents who have bettered themselves and served their new country.
High school student hopes for immigration reform
One Latino advocacy group -- Presente.org -- released a statement before Obama's speech criticizing the president for failing to issue an executive order stopping the deportation of young undocumented immigrants until legislation such as the DREAM Act is passed.