Grassley and Sen. Mike Lee, R-Utah, were among those who offered the border-security amendments, which met opposition from the committee's 10 Democrats and the two Republicans Sens. Lindsey Graham of South Carolina and Jeff Flake of Arizona who helped draft the bill. Sen. Orrin Hatch, R-Utah, supported the border security amendments.
The bill's backers say they must balance the need to protect the southern border with the desire to legalize the 11 million unauthorized immigrants.
"They are in the shadows and we've got to bring them out," said Flake. "It is not a good move to wait on that process."
The current proposal gives the Department of Homeland Security six months to develop a border fence and a separate border-security plan. Once the government starts implementing those plans, it can also start processing applications for the new registered provisional immigration status, which is essentially a temporary work permit.
Grassley offered an amendment that would force Homeland Security to prove it had 90 percent effective control over the entire border for six months before offering the new immigration passes.
Sen. Jeff Sessions, R-Ala., wanted to force the government to construct 700 miles of double-layered border fence before offering green cards.
The committee rejected those ideas on a vote of 6 to 12, with the majority saying the ideas were too onerous and expensive. Lee's amendment was defeated by the same margin.
Lee's proposal would have required Congress to vote on the border-security plan before offering provisional status and then, five years later, vote again on whether the border plan worked before those same immigrants could get a green card. The House and Senate would have 30 days to bring the plan up for a vote and it couldn't be amended or blocked through congressional procedures.
"As written, the bill's border security triggers may be illusory if the legislation provides for legalization and a path to citizenship prior to any actual or demonstrable success in securing the border," Lee said. "It gives broad discretion to the Department of Homeland Security to make unreviewable determinations about easily manipulated security goals."
Graham said Lee's amendment would make sense if there wasn't a deeply embedded political fight over the issue.
"I guarantee you all of our Democratic friends are going to say the border is secure and I guarantee you the Republican House is going to say, 'no, it's not for a very, very long time,' " he said.
Lee's amendment is partially a reaction to questions he asked Homeland Security Secretary Janet Napolitano in a hearing in late April. Napolitano said if the bill passed she would move "very quickly" to certify that the border fence is complete, noting the government has constructed 652 miles of the planned 653-mile fence.
She also said that she has a sector-by-sector border security plan ready to go, touting that the border is more secure that it has ever been, a claim some Republicans say has little meaning.
But Democrats on the panel say security gains under the Obama administration are key. They note the Border Patrol has doubled in size since 2004 and that it has more surveillance equipment, including the use of unmanned aerial vehicles, to guard the 2,100 mile line separating Mexico from the United States.
The bill also provides additional funding for border security and will seek to greatly increase the use of drones to track the number of people crossing the border.
Authorities plan to use those drones to help determine if Homeland Security reaches its goal of apprehending 90 percent of illegal border crossers in high-risk areas along the southern border.
Sen. Chuck Schumer, D-N.Y., one of the bill's authors, said he's confident that once implemented "the border will be effectively closed."
But his Republican colleagues remained largely unconvinced, harkening back to the immigration bill passed in 1986 under President Ronald Reagan, where border enforcement didn't stop illegal immigration, but three million people received legal status.
"The long-standing disconnect between immigration policy and enforcement has created deep distrust that the federal government will, or even can, keep its promises," Lee said.