Hillary Clinton, Bernie Sanders and Martin O'Malley are preparing for their next debate Sunday night in Charleston, South Carolina.WATCH VIDEO HERE. This will be the fourth debate for the Democrats and the last one before the Iowa caucuses.It could be a contentious round, with the latest polls showing Sanders only a few points behind Hillary Clinton.It's make or break time, with a little more than two weeks to go before Iowa's first-in-the-nation caucuses.In the latest Bloomberg/Des Moines Register Poll, Clinton leads Sanders by just 2 percentage points, down from 9 percentage points one month ago, and an all-time high of 20 percentage points.O'Malley holds on at 4 percent while continuing to travel the state looking to broaden his base.KCCI political analyst Dennis Goldford said one reason for Sanders' increase is that some Clinton supporters are leaving her camp and becoming undecided voters."She's had a lot of tough press and a lot of pounding from the GOP where, at their last debate, they spent a lot of time criticizing her and Obama, (more) than they did each other," Goldford said.According to Goldford, the recent surge by Sanders was not anticipated by the Clinton campaign. He said both candidates need to tread lightly when it comes to criticizing each other."They're taking Sen. Sanders much more seriously, and I think at this classic point of the primary, you need to punch back," he said. "But on the other hand, if you win the primary, you need the other person's supporters, too."Differences in approaches to health care and national security are likely to take center stage in Sunday's debate.The discussions on these issues have been civil between Sanders and Clinton, but as the race gets tighter, that could change.

Hillary Clinton, Bernie Sanders and Martin O'Malley are preparing for their next debate Sunday night in Charleston, South Carolina.

WATCH VIDEO HERE.


This will be the fourth debate for the Democrats and the last one before the Iowa caucuses.

It could be a contentious round, with the latest polls showing Sanders only a few points behind Hillary Clinton.

It's make or break time, with a little more than two weeks to go before Iowa's first-in-the-nation caucuses.

In the latest Bloomberg/Des Moines Register Poll, Clinton leads Sanders by just 2 percentage points, down from 9 percentage points one month ago, and an all-time high of 20 percentage points.





O'Malley holds on at 4 percent while continuing to travel the state looking to broaden his base.

KCCI political analyst Dennis Goldford said one reason for Sanders' increase is that some Clinton supporters are leaving her camp and becoming undecided voters.

"She's had a lot of tough press and a lot of pounding from the GOP where, at their last debate, they spent a lot of time criticizing her and Obama, (more) than they did each other," Goldford said.

According to Goldford, the recent surge by Sanders was not anticipated by the Clinton campaign. He said both candidates need to tread lightly when it comes to criticizing each other.

"They're taking Sen. Sanders much more seriously, and I think at this classic point of the primary, you need to punch back," he said. "But on the other hand, if you win the primary, you need the other person's supporters, too."

Differences in approaches to health care and national security are likely to take center stage in Sunday's debate.

The discussions on these issues have been civil between Sanders and Clinton, but as the race gets tighter, that could change.