Update at 3:06 p.m. ET. 'Now Is The Time':
Talking to an audience in Las Vegas, an upbeat President Obama said that "now is the time" for "common sense comprehensive immigration reform."
While Obama echoed the pillars of immigration reform presented by a bipartisan group of senators on Monday, he also made an emotional plea for reform.
"What makes somebody American," he said, "is not just blood or birth, but allegiance to our founding principles."