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. [...] 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. The separate White House and Senate proposals focus on the same principles: providing a way for most of the estimated 11 million people already in the U.S. illegally to become citizens, strengthening border security, cracking down on employers who hire illegal immigrants and streamlining the legal immigration system. Obama and the Senate lawmakers all want to require people here illegally to register with the government, pass criminal and national security background checks, pay fees and penalties as well as back taxes, and wait until existing immigration backlogs are cleared before getting in line for green cards. Another key difference between the White House and Senate proposals is the administration's plan to allow same-sex partners to seek visas under the same rules that govern other family immigration. The Senate principles do not recognize same-sex partners, though Democratic lawmakers have told gay rights groups that they could seek to include that in a final bill. [...] Tuesday, in another sign of Congress' increased attention to immigration issues, a group of four senators introduced legislation aimed at allowing more high-tech workers into the country, a longtime priority of technology businesses.