If years of residency were the measure, Ulises Pacheco of Kansas City would be as nearly American as he is Mexican.

On Tuesday, when President Barack Obama called on Congress to advance an immigration overhaul that includes a plan "that finally deals with the 11 million undocumented immigrants who are in this country now," Pacheco drew cautious hope that it might be so.

That a bipartisan group of senators on Monday announced that the Senate would also work toward reform to include a possible pathway to citizenship made the prospect even more possible.

"It would be the most important thing for me," Pacheco said Tuesday through a translator in the minutes before the president's midday speech at Del Sol High School in Las Vegas.

Age 34 now, Pacheco, who is an undocumented house painter, came to the United States on his own from Mexico City at age 19, nearly half a lifetime ago, "for more opportunity, a better life."

His daughter, Daisy, now 9 and in fourth grade, was born in the U.S. and is a citizen.

His son, Miguel, was also born here as a citizen in summer of 2005. Sadly, he was also born with leukemia.

For nearly six years, Pacheco sat with his son at Children's Mercy Hospital and cared for him at home as a single father until, in July 2011, the boy passed away.

Pacheco carries a tattooed likeness of his son on his left shoulder. The image of Mickey Mouse is inked above the likeness, the Virgin Mary beneath.

The overarching reason Pacheco wants to be a U.S. citizen, he said, is to honor the memory of his son, to provide his daughter with the American dream of a college education and the better life he wanted them to have.

"This is for him," Christina Jasso, who helped translate for Pacheco as case manager at Guadalupe Center Inc., said of the call for immigration reform. "This is for him. He is a hard worker. He is a good man. He is the most dedicated father."

It is difficult to parse, at this early stage, exactly how the president's blueprint for immigration reform will ultimately meld with the version presented by the Democratic-controlled Senate, or any alternative version presented by the Republican-controlled House.

The president warned that "the closer we get, the more emotional this debate is going to become." He said that if Congress did not act quickly enough on its own legislation, he would send up a bill -- something the White House has put off for now.

"The good news is that -- for the first time in many years -- Republicans and Democrats seem ready to tackle this problem together," Obama said. "Members of both parties, in both chambers, are actively working on a solution. And yesterday, a bipartisan group of senators announced their principles for comprehensive immigration reform, which are very much in line with the principles I've proposed and campaigned on for the last few years."

Declaring "now is the time" to fix broken immigration laws, Obama heralded a rare show of bipartisanship between the White House and Senate lawmakers on principles of putting millions of illegal immigrants on a pathway to citizenship, cracking down on businesses that employ people illegally and tightening border security.

Both the White House and Senate proposals still lack key details. And potential roadblocks are already emerging over how to structure the road to citizenship and whether a bill would will include same-sex couples -- and that's all before a Senate measure can be debated, approved and sent to the House, where opposition is likely to be stronger.

Kansas Secretary of State Kris Kobach, a leading architect of laws cracking down on illegal immigration, said that the current call for immigration reform will fail and that eight senators proposing bipartisan reform don't speak for the majority of voters.

"It's silly when politicians of both parties play word games," Kobach said. "They don't call it 'amnesty,' they call it a 'pathway to citizenship.' It's both."

Kobach said "there are some self-appointed leaders in the Republican Party who have declared this is the path forward. Those leaders, like John McCain, are not leaders of the Republican Party."

Despite possible obstacles to come, the broad agreement between the White House and bipartisan lawmakers in the Senate represents a drastic shift in Washington's willingness to tackle immigration. Much of that shift is politically motivated, due to the growing influence of Hispanics in elections and their overwhelming support for Obama in November.

"Everyone is reaching out to us now after the last election," said Guadalupe Center Chief Executive Officer Cris Medina. "It's been a long time coming. It's not as if we just got here. A lot of America's future depends on the Latino community."

At Kansas City's Alta Vista High School, a charter school that primarily serves the children of Latino immigrants, Lesly Vega, 15 of Kansas City, said that any legislation that lifts the fear of deportation from millions of undocumented individuals is a step forward.

Lesly is one of about 40 students at Alta Vista soon to receive a Social Security card, giving her legal status in the U.S. under "deferred action," the policy enacted by Obama in June that allows hundreds of thousands of young people brought illegally to the United States as children to remain as law-abiding residents.

As an only child of a mom and dad, both of whom work in restaurants, she sees reform as a chance for her parents to improve their lives and thus her own.

"I think it offers my parents a great opportunity to find better jobs," she said. "My mom actually wants to go to school. They want me to go to college and be successful."

Mostly, she said, the prospect of lasting reform takes away the fear that parents will be ripped from their children.

"People are excited. Definitely," said Diane Rojas, associate director of health and human services for Guadalupe Centers Inc.

"I think it's just alleviating the fear and giving them that hope. ... The bipartisan group has come up with a blueprint. Now let's hope it's a straight-forward path to citizenship, and not an obstacle course."

The Associated Press and The Star's Dave Helling contributed to this report.