President Obama made his first official visit to the U.S.-Mexico border today where he challenged Republicans to get serious about immigration reform, saying his administration has met their demands for beefed up internal enforcement and border security.
Speaking before a crowd of supporters in El Paso, Texas, Obama said the unprecedented number of border agents and technological resources along the border have significantly reduced the illegal flow of drugs, weapons and humans into the United Staes over the past two years.
The president said the progress should sufficiently allay concerns that have hampered congressional efforts to bring about more comprehensive reform, including steps to address the legal status of the country's estimated 11 million undocumented immigrants and streamline the legal immigration system.
"We have gone above and beyond what was requested by the very Republicans who said they supported broader reform as long as we got serious about enforcement," Obama said. "All the stuff they asked for we've done. But even though we answered these concerns, there are still some who are trying to move the goal posts on us one more time."
Earlier in the day, Obama toured a cargo screening facility in El Paso, where U.S. Customs and Border Protection officers screen hundreds of daily shipments to and from Mexico for guns, drugs, money and radiological threats. He also held conversations with community leaders about the economic implications of reform.
Obama did not offer new details or a timeline for his legislative plan, but he emphasized the emotional and economic arguments for advancing bipartisan dialogue and called on supporters to pressure lawmakers from the outside.
"One way to strengthen the middle class in America is reform the immigration system so that there's no longer a massive underground economy that exploits a cheap source of labor while depressing wages for everybody else," Obama said.
"I'm going to do my part to lead a constructive and civil debate on these issues, he said, "but this change ultimately has to be driven by you, the American people. You've got to help push for comprehensive reform, and you've got to identify areas we can find common ground between Democrats and Republicans and fix what's broken."
Despite the renewed push, nearly two years after Obama first promised to pursue an immigration reform package, many voices on both sides of the debate agree a sweeping bill has virtually no chance of passing Congress any time soon.
The president's speech was widely viewed at least in part as a political appeal to Hispanics, who are a key constituency for his 2012 reelection campaign.
Hispanics voted for Obama by a 2-to-1 margin in 2008. But many have since become disillusioned, hit hard by the sluggish economic recovery and disappointed by unfulfilled promises to improve policies affecting millions of legal and illegal immigrants and their families, community leaders say.
"In the immigrant community across the country, there is broad acknowledgment that Republicans are the single biggest impediment to bringing comprehensive immigration reform to a successful conclusion," Democratic Rep. Luis Gutierrez of Illinois said in an interview Monday.
"But when we had broad, expansive Democratic majorities in both the House and the Senate, where was this call for reform from Obama? Where was the push to get Republicans to the table? Where was the energetic, 'Let's get out there and rev up the troops?'
White House officials said Obama has always been committed to achieving a comprehensive package of immigration system reforms, and that the Texas speech is a renewed "call to action" despite the low political odds.
"We weren't able to achieve it in the first part of this term, the president's term, but it remains a priority of the president's, even though it's hard," White House press secretary Jay Carney said Monday of a broad legislative reform package.
Obama has held three high-profile meetings on immigration in recent weeks, pulling together a diverse mix of stakeholders and lawmakers from across the country to enlist help campaigning for his plan.
He envisions a sweeping law that would make immigration enforcement programs more strategic, penalize employers who hire illegal workers, streamline the visa process and provide relief to thousands of immigrant families living in the shadows.
Most Republicans and some moderate Democrats staunchly oppose any legislation that would address the legal status of the country's estimated 11 million undocumented immigrants, citing concerns about competition for scarce U.S. jobs and added strain on social welfare programs.
Many states have been taking matters into their own hands, passing immigration legislation that strengthens enforcement and in some cases seeks to provide relief to illegal immigrant workers and families.
Immigrant advocates want Obama to use his administrative power to grant at least temporary relief to some undocumented immigrant students and family members of U.S. citizens.
They say he could use a presidential memorandum or executive order to shield selected immigrants from being targets for deportation and possibly remove barriers to a path to legal status in the United States for others.
The White House said earlier this month the president would "carefully review" the requests put forth by immigrant advocates and members of Congress.
"I believe that they are having a serious conversation about what they can and should do," said Ali Noorani, executive director of the National Immigration Forum. "But at the least, all these events Obama has been having put the burden on Republicans, and that's only a good thing."
Opponents of legal and illegal immigration have warned, however, that such a move could cost the president politically.
"I think the president would be handing a tremendous political victory to his opponents for next year's election if he took some administrative action," said Roy Beck, president of Numbers USA, a group that seeks greater immigration restrictions. "Then, it won't just be about immigration, it will be about abuse of executive power.
"He knows no amnesty has any chance. They know it. But they are going around and wanting people to know that it's not his fault so that the pro-amnesty voters will come out and vote better than they did in 2010," Beck said of Obama's speech.
ABC News' Sunlen Miller contributed to this report.