Cory Booker could be in for a shock.

The energetic Newark mayor, who is favored to win Tuesday’s Democratic primary as well as the Senate seat in New Jersey’s special election, is already a national political star and has been boasting about the kinds of things he thinks he can accomplish from a statewide perch. But the man who saved a woman from a burning building, hosted dozens of powerless residents at his home in the wake of Superstorm Sandy, and already has 1.4 million Twitter followers may not be ready for the slow-grinding gears of Congress.

“The Senate’s far bigger than any one senator, no matter how many Twitter followers,” said Jim Manley, a former longtime top Senate Democratic aide who is now senior director at QGA Public Affairs.

That may be true, but Booker clearly believes he will be a major force. He suggested last month that Senate Democratic leaders can’t wait for him to join their ranks after the Oct. 16 special election.

In an interview with Gannett’s New Jersey newspapers in July, Booker said he’ll “be able to have an impact that a freshman senator usually won’t have” because at least one unnamed Senate Democratic leader told him he will be needed “out working for the party” — an apparent reference to his fundraising prowess and appeal on the campaign trail.

“Give me a statewide platform,” Booker told Gannett, “and I will not only continue this stuff at a magnified level all across our state, but in Washington on day one.”

He added, “The ability to rack up favors with people now that are asking me to campaign in tough states from Kentucky to Louisiana, but also experience in working across the aisle on issues because I’ve conservative bona fides, because I’ve been working with their think tanks on practical projects in Newark as well.”

That unbridled ambition and confidence is hardly new for the 44-year-old. He was elected to the Newark City Council in 1998 and he served just four years before challenging, unsuccessfully, the incumbent Newark mayor in 2002. He’s been the city’s mayor since winning an open-seat race in 2006.

There’s no shortage of former mayors who have served in the Senate — more than 100 all told, according to statistics maintained by the Senate Historical Office — but coming directly to the Capitol from a mayor’s office is unusual in modern times.

It’s an open secret on Capitol Hill that former chief executives, such as governors and mayors, can find the world’s greatest deliberative body to be frustratingly inactive. Sen. Mike Johanns, a former Republican governor in Nebraska, is retiring after one term in the Senate — and his successor in the governor’s mansion has now twice turned down opportunities for what would have essentially been free rides to Capitol Hill.

“If you are a public official who is nourished by accomplishment, you are starving in this Congress,” said former Sen. Byron L. Dorgan, D-N.D., who spent 30 years in Congress before retiring in 2011.

Sometimes, former governors have worked together, regardless of party affiliation. That was the case in June, when Tennessee Republican Lamar Alexander, Maine independent Angus King and West Virginia Democrat Joe Manchin III worked on a long-term student loan compromise that ruffled feathers on the Democratic side.

Booker’s campaign did not respond to an interview request, but the Newark mayor has made it clear in debates with Reps. Frank Pallone Jr. and Rush D. Holt and state Speaker Sheila Y. Oliver that he has little patience for legislative inertia.

“It’s time for action and getting things done,” Booker said during an Aug. 5 debate.

But getting things done as a legislator is different than as an executive, as Dorgan pointed out.

“Going from an executive branch … to the Congress is sometimes a shock. In an executive branch post you are in charge — you make decisions and are accountable for the decisions. In the Congress you can’t give orders, you have to find ways to build a consensus or develop coalitions. Very different skills!” Dorgan said in an email. “But good politicians usually possess both skills.”

Booker’s sell to voters has rested largely on what he says was his ability to turn around the state’s largest city during one of the country’s worst economic declines. But it’s his national profile, including as a surrogate for President Barack Obama during the 2012 campaign, that’s allowed him to raise an average of $1.2 million per month this year and made him the favorite to fill the remaining term of the late Democratic Sen. Frank R. Lautenberg.

With Senate control hanging in the balance in 2014 — and the next New Jersey senator up for a full term, as well — it’s not surprising to hear Booker admit that he’s in high demand on the campaign trail already.

Still, Booker hopes to bring his Newark know-how to a capital city beleaguered by partisanship.

“Come on, we are a great economy, and the reality is if we make strategic investments, if Congress actually does something, we can have incredible growth,” Booker said in a debate. “How do I know that? We did it in Newark.”

One way of gauging his interest in being a workhorse instead of a showhorse could come in his first hires as a senator. Two previous Democratic media sensations — Obama and Hillary Rodham Clinton — both hired Senate insiders at the senior staff level for their Senate offices.

Then again, Booker could go after the headlines if, as Manley put it, “he wants to become irrelevant like [conservative senators] Ted Cruz, Rand Paul or Mike Lee.”