“The amnesty is first, virtually immediately. The enforcement is later, maybe," he said.

Other Republicans argued adding millions of undocumented immigrants to America’s legal workforce would depress wages and add to unemployment.

But according to a non-partisan congressional analysis, the Senate bill would boost U.S. economic growth and reduce federal deficits, a projection highlighted by Democratic Senator Charles Schumer.

“Fewer illegal immigrants, higher GDP [gross domestic product], more jobs, reduced deficit," he said. "Who could oppose that?”

Republican Bob Corker was one of many senators who noted the vast contributions immigrants make to America, regardless of their legal status.

"They are walking across our border to work hard, to do all kinds of things. They create companies and they are entrepreneurs. They also raise our kids, they serve us meals, they bring our crops in, they build our homes, they build our buildings. They want to participate in the American dream," he said.

But opposition to the Senate’s vision for immigration reform runs high among Republicans who control the House of Representatives. House Speaker John Boehner has ruled out a vote on the Senate bill.

Instead, the House could pass border security measures mirroring Senate provisions, but skip legalization of the undocumented. An enforcement-only approach would be unacceptable to Democrats, including President Obama.