Republican presidential candidate John McCain said Wednesday that the issue of illegal immigration angered people unlike no other, including the unpopular war in Iraq, and sparked unprecedented death threats against him.

"It is unbelievable how this has inflamed the passions of the American people," the Arizona senator said in remarks at The Aspen Institute, a public policy forum. In an interview, he declined to elaborate on the threats he had received.

Still, McCain said, he continued to support a temporary worker program for the 12 million illegal immigrants in the United States. Derided by critics as amnesty, the program was one of the most controversial elements of the failed immigration bill supported by President Bush and a bipartisan group of lawmakers in the House and Senate.

McCain acknowledged that the immigration issue, along with his support for the war in Iraq, had cost him politically.

"Look, I've got to do what I know is right for this country. These issues I have to take head-on," he said.

McCain said the United States is making progress in Iraq, and he recommended that the U.S. take a hard line against Iran. He said an alternative is needed to the United Nations, where Iran's supporters have blocked sanctions, and that the U.S. should set up another coalition with democratic nations.

Russian President Vladimir Putin should be barred from the next meeting of the G-8, the coalition of western leaders who meet to discuss world issues, McCain said. Putin wants to reunite the former Soviet Union and has surrounded himself with former members of the Soviet spy agency, the KGB, to crack down on opponents, he said.

McCain said the G-8 was founded on fundamental economic and democratic principles and that Russia no longer meets the qualifications for G-8 membership.

"We have to make it clear to Putin that this kind of behavior makes him, in many ways, a pariah. The next year when they're meeting, stay home, Vlad," he said.