U.S. President Barack Obama and Republican challenger Mitt Romney have held their second debate of the campaign, taking questions from undecided voters during a town-hall style meeting at New York's Hofstra University.

After taking questions about energy, the economy, jobs and equal pay for women, an audience member asked Mr. Romney about immigration.

The governor said he would not grant amnesty to illegal immigrants. He said he wants the system for legal immigration to be streamlined and clear so that a would-be immigrant would not need a lawyer to emigrate. He also called for more green cards for skilled workers, and he accused President Obama of failing to keep his promise to carry out immigration reform.

The president said he has done everything he can to fix the immigration system for those trying to come to the country legally. He called the United States a nation of laws, but said he does not want to go after students who have lived in the country for years or people who came to the United States just to feed their families.

Another audience member wanted to find out who denied enhanced security for the U.S. consulate in Benghazi, Libya and why.

Mr. Romney accused the president of taking two weeks to tell the American people that the attack on the consulate, killing the U.S. ambassador and three others, was an act of terrorism. He said the Obama Middle East policy is unraveling.

The president said he called the Benghazi attack an act of terrorism on the following day. He said the suggestion that anyone in his government would use the violence in Libya to play politics or mislead the American people is offensive.