Menendez was one of a clutch of senators who last week signed off on a plan to boost border patrols by 20,000 agents, an agreement supporters hope will be the breakthrough needed to win over more Republicans and get the immigration package through the Senate. A vote is expected this week.
The issue is personal for Menendez, the son of Cuban immigrants and one of only three Hispanic senators, but there are also implications for other local lawmakers.
Sen. Pat Toomey (R., Pa.) is being eyed as a potential GOP supporter who could help the bill garner an overwhelming bipartisan majority. Voting for a bill that is one of President Obama's top priorities would boost Toomey's centrist credentials but could hurt his standing with conservatives who felt betrayed this year when he sponsored a plan to expand background checks for gun purchases.
For interim Sen. Jeffrey S. Chiesa (R., N.J.), the vote may be the biggest of his four-month tenure. His stand could also affect how national Republicans view Gov. Christie, who handpicked Chiesa this month to replace the late Sen. Frank R. Lautenberg.
Toomey and Chiesa have each raised concerns about border security, but neither has taken a firm position on the bill. Sen. Bob Casey (D., Pa.) supports the plan.
But the measure means the most for Menendez. He hails from Hudson County - now 42 percent Hispanic - and has long fought for immigration reform.
As much as Sen. Marco Rubio (R., Fla.), a fellow Cuban American, has worked to persuade conservatives while also advocating for the right's priorities, Menendez has emerged as a liaison and gatekeeper for the left on the issue.
"Menendez is clearly the Latino community's voice and champion in this process," said Janet Murguìa, president of the National Council of La Raza, which calls itself the largest Hispanic civil rights group in the country. "It's Sen. Menendez who maintained a very firm line on the community's aspirations and interests. . . . He has been the conscience of the group and is not afraid to pull the group back when they go too far."
Menendez has insisted on two principles: creating an attainable "pathway to citizenship" for the country's 11 million undocumented immigrants, and preserving the right of legal immigrants to petition to bring close family members to the country.
But he also swallowed compromises.
To build a winning alliance, the Gang of Eight has had to blend interests of liberals and conservatives, high-tech and agriculture, business and labor, security and immigrant rights.
In interviews, three Republicans in the "gang" credited Menendez. "Without him we couldn't have gotten as far as we have," said Sen. Lindsey Graham (R., S.C.). "He's been helpful with the Hispanic community saying, 'You've got to give some.' "
The bill would tilt future immigration preferences toward highly educated, high-skilled applicants, while limiting some family reunification provisions. Legal residents, for example, could petition to bring only married children 31 and younger to the United States, instead of all children, as the law now allows. The road to citizenship is envisioned as a 13-year trek, longer than many Hispanic groups had hoped for.
Menendez's history of advocacy, though, gave him the standing to persuade Latino groups. Viewers across the country know him from appearances on Spanish-language news shows, and trust him, Sharry said.
"He said at the beginning: 'I'm going to stretch for a deal. I'm going to say yes to things that you're not going to like,' " he said. "He's a blunt guy - sometimes blunt to a fault - but you don't have to question where he stands."
The final step, the Gang of Eight hopes, was the "border surge" they agreed to last week in a bid for additional Republican support.
"This is the price to pay in a compromise to get what I think will be a very strong bipartisan vote," Menendez told The Inquirer on Thursday after an interview with the Spanish-language channel Univision.
But he added that he had gone as far as he could on security. "The store is closed," he said.
The deal on expanded border security was meant not only to help win Senate passage, but to do so in big, bipartisan fashion - 70 or more votes - and thus put pressure on the House, where many conservatives are hostile to the plan.
What Menendez calls a "pathway to citizenship" critics label "amnesty" for those who broke the law to come here. Some border-state Republicans also warn that previous security promises have been broken and predict that a flood of new workers will drive down wages. "We're going to have twice as many people coming to the country on visas, and they're going to take jobs," said Sen. Jeff Sessions (R., Ala.).
But in recent weeks, Menendez has taken on an increasingly public role pushing back.
On MSNBC he accused Sen. Ted Cruz (R., Texas) of opposing the bill out of "Obamaphobia." On CNN he warned, "There will never be a road to the White House for the Republican Party" without a path to citizenship for Latino immigrants.
He held an online "town hall," answering questions in English and Spanish, and took queries on Twitter, using the hashtag #AskMenendez.
"He has always been approachable, he has always listened, and that's rare in a senator," said the Rev. Luis Cortes Jr., president of Esperanza, a Philadelphia-based coalition of faith-based Hispanic groups.
Menendez walked away from 2007 immigration-reform negotiations when he thought the plan had strayed too far, but he doesn't see a similar possibility this year.
Not when he thinks the solution is closer than at any time in his 20-year congressional career.
Contact Jonathan Tamari
at email@example.com. Follow on Twitter @JonathanTamari. Read his blog 'Capitol Inq' at www.inquirer.com/CapitolInq.