LAS VEGAS — Seizing an opening to rewrite the nation’s immigration laws, President Obama challenged Congress on Tuesday to act swiftly to put 11 million illegal immigrants living in the United States on a clear path to citizenship.
But his push for speedy action and his silence on proposals to defer the opportunity for legal residency until the borders are deemed secure provoked criticism from a Republican leader on the issue. The response suggests that reaching consensus on immigration law changes remain difficult despite a new bipartisan push since the November elections.
Speaking at a high school in a state that has seen rapid growth in its Hispanic population, Obama praised a bipartisan group of senators that proposed its own sweeping immigration overhaul a day earlier, saying the plan was very much in line with his own proposals.
He warned, however, that “the closer we get, the more emotional this debate is going to become.” He said that if Congress did not move forward “in a timely fashion” on its own legislation, he would send up a specific measure — something the White House has put off for now — and demand a vote.
The president’s speech immediately exposed potential fault lines in the coming debate. He said, for example, that there must be a path to citizenship for illegal immigrants “from the outset,” a statement that would seem at odds with the assertion by some senators that citizenship must be tied to tighter border security.
Senator Marco Rubio, a Florida Republican who is seen as an influential party voice on an issue that cost Republicans in last year’s voting, said he is “concerned by the president’s unwillingness to accept significant enforcement triggers before current undocumented immigrants can apply for a green card.”
“Without such triggers in place,” he went on, “enforcement systems will never be implemented, and we will be back in just a few years dealing with millions of new undocumented people in our country.”
Although Obama did not say it in his speech, the White House is also proposing that the United States treat same-sex couples the same as other families, meaning that people would be able to use their relationship as a basis to obtain a visa — another element likely to be resisted by conservative Republicans.
Brendan Buck, a spokesman for Speaker John Boehner, said in a statement that House Republicans “hope the president is careful not to drag the debate to the left and ultimately disrupt the difficult work that is ahead in the House and Senate.”
Obama’s speech, on the heels of the bipartisan Senate proposal, sets the terms for one of the year’s landmark legislative debates. These are only the opening steps in a complicated dance, and both the politics and the policy can be treacherous ground, as shown by the failed effort to overhaul immigration laws in George W. Bush’s administration.
But the flurry of activity underscores the powerful new momentum behind a system overhaul, after an election that dramatized the vulnerability of Republicans on the issue, with Obama piling up lopsided majorities over Mitt Romney among Hispanic voters.
“Most Americans agree that it’s time to fix a system that’s been broken for too long,” Obama said to an audience of about 2,000 high school students, many of them Hispanic. They applauded loudly when he mentioned the Dream Act, which offers amnesty to children of immigrants who are in the United States illegally.
In scrambling to present their blueprint on Monday, the day before Obama’s speech, the senators stole a march on the president. But their intent appeared less to undermine his efforts than to stake out their own role in drafting a comprehensive bill.
‘’It is a fascinating Washington horse race that you don’t always see, and a signal of the seriousness to get across the finish line,’’ said Angela Kelley, an expert on immigration at the Center for American Progress, a liberal research group.
With the senators hoping to pass legislation by this summer, the White House has shelved, for now, plans to introduce its own immigration bill, officials said. Indeed, after two years of feuding with Congress, Obama finds himself in rare alignment with Democratic and Republican lawmakers on at least the need to address a major issue.
That is what made Obama’s speech such a novelty: rather than criticize Congress as do-nothing and obstructionist, as he did nearly every day during the campaign, he applauded the lawmakers for racing ahead of him, at least for a day.
Beneath the expressions of harmony, however, Kelley cautioned: ‘‘There’s so much they don’t agree on. There’s going to be a lot of soul-searching.’’
Among the main differences is whether to make the path to citizenship for illegal immigrants contingent on stricter border controls and visa procedures.
Obama, in his remarks, emphasized that as long as immigrants registered with the authorities and fulfilled other obligations like paying their taxes, there should be no doubt that they would eventually obtain citizenship.
‘‘If you’re able to meet some basic criteria,’’ he said, ‘‘we’ll offer you the chance to come out of the shadows.’’
Obama defended his record in securing the borders, saying that illegal border crossings had dropped 80 percent from their peak in 2000 because of increased patrols. Six unmanned surveillance drones now fly over the southwest border, in addition to 124 other aircraft.
Obama’s remarks differed little from the main points in his 29-page blueprint for overhauling immigration laws, which he issued in May and used as a plank in his reelection campaign. But his language was plainer and more forceful — speaking of a road to citizenship for illegal immigrants, for example, not merely to legal status.