Barring a major surprise, Newark Mayor Cory Booker (D) will be Sen.-elect Cory Booker by day’s end.

It’s hard to imagine a more turbulent and pivotal moment for Booker — who, if he wins, could be sworn in as early as this week — to enter the Senate. His first vote might be on a bill to reopen the government and pull the country back from the brink of a debt ceiling disaster.

Despite running a lackluster campaign, Booker is expected to defeat Republican Steve Lonegan in a rare Wednesday special election for the seat once held by the late senator Frank Lautenberg (D). (For more on why the election is being held on a Wednesday, read this.) Polls show him up by double-digits over Lonegan, a tea party Republican whose political views are more conservative than most New Jerseyans.

Booker is one of the Democratic Party’s rising young stars. He is at once a celebrity and politician, something Lonegan sought to use against him, with some success. Now, Booker is set to become but one of 100 senators — the junior-most member of a chamber steeped in tradition and seniority.

The question is how Booker would fit in. As we’ve argued in this space before, while the upper chamber has a crop of young visible and vocal Republican stars like Sens. Ted Cruz (Tex.), Marco Rubio (Fla.) and Rand Paul (Ky.), they don’t have any real Democratic counterparts. Booker seems poised to become one. Never one to shy away from the spotlight or speak his mind, Booker could well emerge as the Democratic analog to Rubio/Cruz/Paul.

We know this much: He’ll have plenty to talk about if, as expected, he arrives in Washington as the newest member of the Senate. Senate leaders are closing in on a deal to reopen the government and raise the debt ceiling after talks collapsed in the Republican-controlled House on Tuesday. They are rushing to hash out a deal with the clock ticking. Thursday is the day the Treasury has said the country will reach the limit of its borrowing authority. As soon as New Jersey certifies the result of Wednesday’s election, Booker, if he wins, could be sworn in. Democratic leaders aren’t expected to drag their feet.

Booker would replace Sen. Jeff Chiesa (R), a political appointee of Gov. Chris Christie (R). Christie appointed Chiesa, his close ally, as a placeholder until the election. If Booker replaces Chiesa, there would be 55 senators who caucus with the Democrats, compared to 45 Republicans. Here’s why that matters: With a 60-vote threshold becoming the norm for contentious legislation, Majority Leader Harry Reid (D-Nev.) will take every reliable Democratic vote he can get.

The question that has consistently surrounded Booker the past few years has been “what’s next?”

We’re about to find out.