By Cleve Bryan

MOUNT LAUREL, N.J. (CBS) — The stage is set for Tuesday night’s CBS News Democratic presidential debate in Charleston, South Carolina. Seven candidates will face-off for the final time before Saturday’s South Carolina primary.

Former Vice President Joe Biden is leading in the South Carolina polls but national front-runner Vermont Sen. Bernie Sanders will likely have a target on his back.

Debates, as well as polls, sometimes shape how we see candidates — who we see as having momentum or losing momentum and a lot of that information is compiled in New Jersey.

Tuesday night’s performances will have a big impact on how the presidential candidates do in future polls. Some of the experts that measure those trends are right in our region.

“The biggest impact a debate can have is if you stumble,” Monmouth University’s Polling Institute Director Patrick Murray said.

When it comes to measuring political trends, Monmouth University’s Polling Institute is one of the nation’s leading independent polling operations.

During the presidential primary season, their work is in high demand from media and campaigns. But Murray says it’s important to remember polls are not future predictors, they’re snapshots of the present.

“One of the problems with a presidential nominating process is that the first few contests are filled with voters who change their mind at the last minute,” Murray said. “You walk into the room and you vote for someone different than just a few hours beforehand.”

When it comes to debates, the polls from Monmouth help determine which candidates qualify to take the stage.

Depending on the timing of a poll, they can help gauge who performed well in a debate, although Murray says most debate viewers already have their minds made up.

“You already have your core group of supporters and people who think they are going to support you. Did you do anything in the debate that makes them doubt that choice?” he said.

Right now, Monmouth students and paid phone bank workers from Braun Research in Mount Laurel are working on compiling data for a poll on South Carolina’s primary this weekend.

Murray says the candidate he’ll be watching is Biden.

“I think tonight’s debate could be a big game-changer because Joe Biden is the one who needs the big win in South Carolina coming up on the weekend,” Murray said. “So this debate could make or break him in terms of if he’s able to carry on.”