LAS VEGAS (AP) — Declaring "now is the time" to fix broken immigration laws, President Barack Obama on Tuesday urged Congress to put millions of illegal immigrants on a clear path to U.S. citizenship while cracking down on businesses that employ people illegally and tightening security at the borders. He heralded a rare show of bipartisanship between the White House and Senate leaders on basic plans to resolve the long, emotional national issue.

But both the White House and Senate proposals for tackling the complex and emotionally charged issue still lack key details. And potential roadblocks are already emerging over how to structure the avenue to citizenship and whether a bill would cover same-sex couples — and that's all before a Senate measure can be debated, approved and sent to the Republican-controlled House where opposition is likely to be stronger.

Obama, in the heart of the heavily Hispanic Southwest, praised the Senate push, saying Congress is showing "a genuine desire to get this done soon." But mindful of previous immigrations efforts that have failed, Obama warned that the debate would become more difficult as it gets closer to a conclusion.