(Michael Ip/ABC News)

Tonight's presidential debate is a key opportunity for Republican nominee Mitt Romney to prove that he has what it takes to be commander-in-chief, according to three undecided voters who questioned the candidates at the second presidential debate at Hofstra University on New York's Long Island last week.

"I feel that he's a very good businessman," said Nina Gonzalez, undecided voter who was asked about Romney. "But as for representing our country, I get nervous. He went to England and he said 'you guys did a terrible job,' I'm paraphrasing.

"In my opinion you don't go there and say you messed up."

(Click HERE for the debate transcript)

After questioning both Romney and President Barack Obama during last week's domestic policy debate, Gonzalez, Jeremy Epstein and Barry Green told ABC News that they are still undecided.

Epstein, a college undergraduate who asked the first question at the Hofstra debate, said that he is waiting until after the final debate to make a final decision.

(Click HERE for live fact checking)

But he said that Romney's interruptions in the last debate led him to question his steadiness in making foreign policy decisions.

"He's very passionate and I think him being impulsive, it's not settling to me that he's ready to be commander-in-chief," Epstein said. "Because what if something happens on U.S. soil, or something happens like the attack in Benghazi and he just reacts out of impulse and he doesn't consider everything?"

But a third questioner, Barry Green, said that foreign policy experience may be something Romney can learn on the job. Green voted for Obama in the last election.

"Was President Obama ready to take over?" Green said. "He didn't really have that much foreign policy experience before. It's a tough thing that people are going to learn on the job."