WASHINGTON - New Jersey Sen. Bob Menendez took a seat at the head of the dais and looked down toward John Kerry, a towering figure in American politics.

"Yours is a big chair to fill," Menendez said.

He meant it as praise, but Menendez's words Thursday also foreshadow the challenge and opportunity awaiting the fast-rising Democrat as he prepares to assume a larger role in Washington and, perhaps, on the world stage.

Menendez is expected to become chairman of the Senate Foreign Relations Committee after Kerry (D., Mass.), the current chairman, becomes President Obama's secretary of state. The Senate's all-but-certain confirmation vote on Kerry is scheduled for Tuesday.

Menendez would follow a man who was once nearly president, a widely traveled statesman who helped Obama defuse volatile situations in Pakistan and Afghanistan. The two previous chairmen were also Senate giants: Joe Biden of Delaware, now vice president, and Richard Lugar of Indiana.

For Menendez, following their paths will mark another step in a relentless rise from modest beginnings. It will also set a high bar for success.

"I know the importance of the committee," Menendez said Friday. "I certainly know that when the chairman speaks, it has weight both at home and across the globe and I'm very cognizant of that responsibility."

Smart and willful, Menendez will need to expand his focus from a handful of issues and the Western Hemisphere subcommittee he now chairs to a worldwide view.

"You take on a much larger role, and the impact you have on foreign policy is that much greater," said Sen. Bob Casey (D., Pa.), a member of the committee.

Menendez has a reputation as a more confrontational figure than Kerry, sometimes prosecutorial in tone, often described as a "street fighter" who rose through Hudson County, New Jersey's most ferocious political battleground. He has at times clashed with the White House, and he rarely betrays any hint of a softer side.

The son of Cuban immigrants, Menendez notes that he will be the first Hispanic chairman of the committee. He will have a larger platform for his tough stands on Iran and Cuba, as well as oversight of national security and diplomatic issues.

"It's one of the most important positions in the government for influencing policy," said Carol Lancaster, dean of Georgetown University's School of Foreign Service. "They can put issues on the agenda that force the administration to address them."

Menendez will lead the committee as the United States deals with Iran and North Korea's nuclear ambitions, continued Middle East upheaval, violent conflict in Mali, and an accelerating transition in Afghanistan.

After the assault that killed four Americans in Benghazi, Libya, Menendez has stressed steps to improve security at American outposts, saying last week it would be a top priority. 

Though most foreign policy is established by the White House and State Department, as chairman, Menendez can lead hearings that draw scrutiny to issues, ramp up pressure, or bolster the president's decisions.

Biden, for example, used hearings to focus attention on the Iraq war. Menendez, in a preview of his new job, presided over the politically charged session Wednesday in which departing Secretary of State Hillary Rodham Clinton testified on the Benghazi attacks. He then led the hearing on Kerry's nomination.

After each event, reporters from the United States and abroad awaited his words. He spoke first to English-language media, then switched to Spanish for the Spanish-language reporters.

On Sunday, he is to appear on ABC's This Week, opposite Sen. John McCain (R., Ariz.), another member of the committee, which is packed with Republican power. Florida's Marco Rubio and Kentucky's Rand Paul also hold seats.

The son of a seamstress and a carpenter, raised in a Union City tenement, Menendez still begins his days at the IHOP there when he is home in North Bergen.

But he is experienced in foreign policy. He has sat on the Foreign Relations Committee since 2007, after 13 years on the corresponding House panel. He opposed the war in Iraq, and made that stand a central piece of his 2006 campaign for Senate.

His parents having emigrated shortly before Fidel Castro's rise, Menendez forcefully pushes back against all efforts to ease relations with Cuba.

On Iran, he muscled tough sanctions through the Senate, bristling when the Obama administration publicly asked him to relent, drawing attention to his defiant streak. He said he and the White House were on the same page "98 percent" of the time.

"Sometimes, just the slightest set of different views gets overplayed," he said. "I'm looking forward to working very closely with the administration, but I will always have my degree of independence on the things I care about."

It's a busy time. Along with working on the relief bill for Hurricane Sandy, Menendez sits on the powerful Finance Committee. Having broken barriers for Hispanics at nearly every step in his career, he is one of a handful of senators working toward a deal on immigration reform.

People who have worked with him said he was more than just a scrapper.

"He does the reading," Casey said, joining others who praised Menendez's intelligence and preparation. Sen. Bob Corker of Tennessee, the top Republican on the committee, credited what he called his thoughtful, serious approach.

Menendez "understands the politics and the policy," said Andrew Kauders, a former senior aide in the House.

He'll now test those abilities on a worldwide stage. It's a moment of robust possibilities.