NEW HAMPSHIRE (CBSDFW.COM) – Seven Democratic Presidential candidates square off in New Hampshire tonight, several days before that state’s primary.

Vermont Senator Bernie Sanders, former South Bend, Indiana Mayor Pete Buttigieg, Massachusetts Senator Elizabeth Warren, former Vice President Joe Biden, Minnesota Senator Amy Klobuchar, billionaire Tom Steyer, and entrepreneur Andrew Yang all qualified for the debate in Manchester.

READ MORE: Former 737 Max Chief Technical Pilot Enters Innocent Plea To Charge He Deceived The FAA

Matthew Wilson, an Associate Professor of Politics at SMU, said tonight’s debate is important because it will give the candidates one last chance before Tuesday’s primary to re-set the race.

Wilson said he expects former Vice President Joe Biden to be more aggressive after he finished a distant fourth in Iowa.

“Biden has tried so far to kind of float above the fray not really attacking anybody. He doesn’t have the luxury of that anymore. He’s going to have to come out swinging against Buttigieg and against Bernie Sanders because otherwise, he’ll just be drummed out of this race before he can get a foothold.”

While many of the candidates have been targeted by the others at some point during the past few months, Professor Wilson said Sanders has not been.

Wilson said he will be looking to see if any of the candidates attack Sanders and question whether he can beat President Trump in November. “If people keep their powder dry and treat Bernie Sanders with kid gloves, waiting to be the last-standing Sanders alternative, they may wait too long and Sanders might be the nominee.”

READ MORE: Arlington High School Lockdown Lifted After Student Found With Airsoft Gun

Wilson said voters don’t respond to subtlety, they respond to strong, straight-on contrasts and negative attacks.

Sanders has surged during the past several weeks and Buttigieg has surged this week after both tied in Iowa.

While the race appeared to be a two person race between Biden and Sanders heading into the Iowa Caucus Monday, it now looks like a two person race between Buttigieg and Sanders in New Hampshire.

In the Real Clear Politics average of polls in New Hampshire, Sanders remains in first place at 26.7%, but Buttigieg has surged to second place in three days by nearly nine points to 22%.

Warren and Biden are tied for third place with 13%.

Klobuchar is in fifth place with 8%.

MORE NEWS: Students At North Texas High School Stage Walkout In Protest Of Alleged Student Sexual Assault

Follow Jack on Twitter & Facebook: @cbs11jack