President Barack Obama’s allies in organized labor and progressive groups are drawing a line in the sand when it comes to so-called “triggers” that would require a secure border as a precondition to allowing undocumented immigrants a pathway to citizenship.

Left-leaning groups told the president during a meeting this week that any preconditions on creating a pathway to citizenship would be a deal-breaker in terms of winning their support.

 “That is not the starting point,” said Marielena Hincapie of the National Immigration Law Center when asked about part of the Senate’s bipartisan immigration reform proposal that would make prospects for full citizenship contingent on increased border security. “What we are demanding is a road to citizenship that's clear, that's direct, not contingent at all on additional enforcement.” 

The concept is one of the “basic legislative pillars” of a bipartisan Senate proposal on comprehensive immigration reform. While vague, the language is geared towards conservative lawmakers who want tough enforcement mechanisms in place before a path to citizenship can be formed.

The second of the Senate’s four pillars reads: “Create a tough but fair path to citizenship for unauthorized immigrants currently living in the United States that is contingent upon securing our borders and tracking whether legal immigrants have left the country when required.”

The trigger has been an essential component for conservatives like Florida Sen. Marco Rubio, one of the four Republican senators to help craft the plan.

“I will not be supporting any law that does not ensure that the enforcement things happen," he told conservative blogger Ed Morrisey in late January.

Yuri Gripas / Reuters

President Barack Obama waves as he walks on the South Lawn of the White House on Feb. 6 before his departure to Annapolis, Md.

But progressive groups have been ratcheting up the pressure on the president, whom they assert agrees about the concept of a trigger.

“There is clear alignment between us and the president and we look forward to expressing that power as the debate carries forward,” said Marshall Fitz of the Center for American Progress, adding, “We're going to focus like a laser beam on the path to citizenship.”

While White House press secretary Jay Carney seemed to split the difference between the two approaches, saying the president remained committed to both border security and a path to citizenship, but not going so far as to link the two.

“He remains, as part of the comprehensive immigration reform process, committed to increasing our border security further,” Carney said. “But when we talk about comprehensive immigration reform, we're talking about a whole package that moves as a whole, and that includes a clear path to citizenship for people who are affected here,” Carney said.

Cornell University Law School professor Stephen Yale-Loehr, an immigration law expert, said one possible compromise between the two sides would be an enforcement mechanism based on objective criteria, like a certain number of Border Patrol agents along the border or amount of money spent on security.

But he said that if Republicans insist on a subjective measure, such as whether a poll finds the majority of Americans think the border is secure, or whether Republican governors of border states agree the border is secure, common ground will be much more difficult to find.

Asked about the political feasibility of objective measures in a final immigration bill, Yale-Loehr said, “I would hope than an objective one would satisfy the conservatives enough that they could live with it while not antagonizing the other side too much.”