Republican presidential hopeful Rep. Duncan Hunter Sunday lauded San Diego's success in cracking down on illegal immigration and said the United States should be wary of China using U.S. dollars to build a "war machine."Appearing on ABC's "This Week with George Stephanopoulos," Hunter said criticism of President George W. Bush's Iraq policies in the media was lowering morale of the troops.Hunter, whose son is serving his second tour of duty in Iraq, said he believes the American people support sending more troops as reinforcements to Iraq.Hunter, R-Alpine, also said he opposes amnesty for immigrants in the United States without legal papers."We send thousands of people back every week and I think it's wrong for us to send a message to the great Border Patrol of this country and all of the people that work to make sure that people are here legally to say 'you know we really don't believe that stuff,"' Hunter said."All we're saying with respect to the fence is we've got this big front door in America -- legal immigration. Knock on the door if you want to come into the United States."The wall in San Diego, he said, was proof that a massive fence across the U.S-Mexican border could work."We have reduced smuggling of people and narcotics by more than 90 percent in that smuggler's corridor between San Diego and Tijuana," he said. "That the fence works in San Diego."Although the Sunday morning interview programs draw relatively few viewers -- "This Week" attracted about 2.88 million viewers and was seen in 2.1 percent of the nation's television households last Sunday, according to Nielsen Media Research -- they generate both television and newspaper coverage and are watched by many in government and the news media.The interview, which aired at 8 a.m. on KGTV-TV Channel 10, was conducted in South Carolina, the second state to hold a Republican presidential primary, scheduled for Feb. 2, 2008, five days after New Hampshire primary.Hunter has been campaigning in the state since Thursday, when he formally declared his candidacy.Hunter is scheduled to travel to New Hampshire late Sunday and campaign there Monday.Hunter, 58, was elected to the House in 1980 and re-elected every two years since. He was chairman of the House Armed Services Committee from 2003 until the Democratic takeover of the House earlier this month.Hunter has billed himself as the most conservative Republican presidential candidate, which he said gives him a chance for victory despite low name recognition.If elected, Hunter said he would change the way the United States does business with China, which he said could become an enemy."If this was a football team, and we were in the NFL, every other team in the NFL would get points on the scoreboard before the game opened because they (China) have preferential tax and tariff laws," he said, adding that he was concerned about China's military capabilities."They're smart, they've got dedicated engineers and they're going at our strengths in terms of stealth and in intelligence and our ability to penetrate enemy air space," Hunter said. "So China is building a war machine - we see that with our intelligence - they're building it with American trade dollars. That doesn't make sense."In addition to having to overcome low name recognition and being at 1 percent in several polls among Republican presidential hopefuls, Hunter will also have to overcome history to be elected president. No sitting member of the House has been elected president since Republican James A. Garfield in 1880.