The battle that's been brewing for months over who will become New Jersey's next U.S. senator may well be decided by Jon Corzine (search), the man who's got the job now.

One thing has to happen first: Corzine, the Democratic candidate for governor, has to win Tuesday's election. State law gives the governor the power to fill a Senate vacancy.

There are three Democratic congressmen openly vying for the appointment — Reps. Robert Andrews, Robert Menendez and Frank Pallone. All three are campaigning heavily for Corzine, sometimes acting as surrogates at events the senator cannot attend.

Two other Democrats also have been mentioned as possible choices: Rep. Rush Holt and acting Gov. Richard Codey.

Corzine's Senate term ends in 2007, but if he wins the governor's race, he'll resign and move to that post in January. In a Quinnipiac University poll released Monday, he had 52 percent support to Republican Doug Forrester's 45 percent in a survey that questioned 775 likely voters. The sampling error margin was plus or minus 3.5 points.

If Corzine wins, who has the edge to replace him in the Senate? The front-runner has been Menendez for much of the summer, but attention has now turned to Codey, who is popular in the state. New Jersey's former Democratic Sen. Bill Bradley gave Codey a boost recently when he said he liked the sound of "Senator Codey."

Rider University political analyst David Rebovich says he still believes Menendez will get the appointment.

"Menendez has the experience and leadership positions in Washington already," said Rebovich, referring to the lawmaker's status as the House Democratic Caucus chairman, the party's third most powerful congressman. "Menendez in the Senate is also helpful to the national Democratic Party, who want someone strong in there."

Menendez is a close ally of Corzine and is the only congressmen who participates in the senator's campaign strategy meetings every Monday.

Rutgers University political science professor Ross Baker said Holt has been very visible lately in Congress as a member of the House Select Intelligence Committee. Holt has been vocal in his criticism of President Bush (search) and Karl Rove in the CIA leak investigation. And Holt has managed to win election to the House four times in a Republican district.

While Corzine, the former chairman and CEO of Goldman Sachs, was a political novice when he decided to run for the U.S. Senate in 2000, his five potential choices are not. Andrews, Codey, Menendez and Pallone are native New Jerseyans and still live in areas where they grew up. Holt, who was born in West Virginia but grew up in the Washington, D.C. area, moved to the state about 15 years ago to work at the Princeton Plasma Physics Laboratory. His father was a U.S. senator from West Virginia, and his mother served as West Virginia secretary of state.

Menendez, Andrews and Pallone have all said that if Corzine chooses to appoint a caretaker, meaning someone who would not run in 2006, they would jump into the primary race. But all three said they would have to decide whether to run for the full term in 2006 if Corzine decided to appoint a congressmen now.

Holt said he was not certain yet if he would run in 2006. Codey, a longtime state lawmaker, has said being part of the Senate has a certain appeal, but he's not certain it would be enough to lure him in.

Baker said he doubts Corzine would appoint a caretaker. Republicans already have a strong Senate candidate for 2006 in state Sen. Tom Kean, Jr., the son of former Gov. Thomas Kean.

"Whoever is appointed by Corzine comes with an incumbent advantage," Baker said. "You can establish yourself quite firmly in a year, raising lots of money and developing name recognition. Whoever gets it would be regarded as the front-runner for the 2006 election."