The scene unfolded during a raucous rally at a University of Central Florida arena in Orlando, Florida, that featured frequent interruptions by protesters over Trump's hour-long address.
"Let's do a pledge. Who likes me in this room?" Trump asked the crowd. "I've never done this before. Can I have a pledge? A swearing? Raise your right hand."
The Republican front-runner then had the audience repeat after him.
"I do solemnly swear that I, no matter how I feel, no matter what the conditions, if there are hurricanes or whatever, will vote on or before the 12th for Donald J. Trump for President."
The crowd ended the pledge with cheers.
"Now I know. Don't forget you all raised your hands. You swore. Bad things happen if you don't live up to what you just did," Trump said before continuing with his speech.
The Florida Republican primary is on March 15.
Just before leading the rally in the pledge, Trump once again opened the door to ordering the torture of captured suspected terrorists, just one day after vowing
that he would not order military officials to violate U.S. or international laws.
"We're going to stay within the laws. But you know what we're going to do? We're going to have those laws broadened because we're playing with two sets of rules: their rules and our rules," Trump said pointing to ISIS's tactics, which have included torture and brutal executions.
The comments mark a stark contrast to a statement Trump issued just a day earlier. After vigorously defending the use of waterboarding and suggesting that the U.S. should "go a lot further than waterboarding," Trump vowed Friday in a statement that he would "not order our military or other officials to violate those laws."
Trump's conflicting statements on torture come after Trump took heat from former national security officials like former CIA Director Michael Hayden, who argued that U.S. military officials would not follow any illegal orders issued by Trump as president.
"We have to obey the laws, but do you think ISIS is obeying the laws?" Trump asked his supporters on Saturday.
The fervor at Trump's rally also came from protesters, who interrupted Trump's speech more than a dozen times. At one point, the protests became so frequent that Trump asked them to stop so he could hit key points in his stump speech.
"Can the protesters stop for a couple of seconds so we can talk?" Trump asked.
The most notable incident occurred when two young men sitting behind the stage shouted at Trump before a supporter grappled with one of them. An attendee wearing a white Trump shirt grabbed one of the protesters by the neck, attempting to force him out of the venue.
The altercation happened with Trump standing nearby, and at one point he left his podium to approach the protesters. It's unclear if Trump said anything to the men, who were vigorously shouting at the GOP front-runner as attendees around them attempted to wrangle them.
After the protesters were ejected, Trump remarked on "the hatred, the animosity" and the division in America today, seemingly laying the blame at the feet of President Barack Obama.
"You know, we have a divided country, folks. We have a terrible president who happens to be African-American. There has never been a greater division than just about what we have right now. The hatred, the animosity. I will bring people together. You watch," Trump said.