A top adviser to John McCain said another terrorist attack on US soil would be a "big advantage" for the Republican presidential candidate, drawing a sharp rebuke Monday from both the presumed GOP nominee and Democrat Barack Obama. Charlie Black, already in the spotlight for his past lobbying work, is quoted in the upcoming July 7 edition of Fortune magazine as saying such an attack "certainly would be a big advantage to him." Black said Monday he regretted the comment. Black is also quoted as saying the "unfortunate event" of the assassination of former Pakistani leader Benazir Bhutto in December 2007 "helped us." Questioned about Black's comments during a news conference, McCain said, "I cannot imagine why he would say it. It's not true. I've worked tirelessly since 9/11 to prevent another attack on the United States of America. My record is very clear." Citing his work to establish a commission to investigate the Sept. 11, 2001, terrorist attacks and his membership on the Senate Armed Services Committee, McCain added: "I cannot imagine it, and so, if he said that - and I don't know the context - I strenuously disagree." Obama spokesman Bill Burton said in a statement: "The fact that John McCain's top adviser says that a terrorist attack on American soil would be a 'big advantage' for their political campaign is a complete disgrace, and is exactly the kind of politics that needs to change. Barack Obama will turn the page on these failed policies and this cynical and divisive brand of politics so that we can unite this nation around a common purpose to finish the fight against al-Qaida." The remarks caught McCain flat-footed on a day when he focused on energy issues - first in a speech, then at a town-hall meeting and then during a news conference as he stood beside two $100,000 electric cars. McCain offered $300 million to anyone who develops a revolutionary automobile battery, and he predicted such incentives would lower alternative energy costs. Moments later, he was befuddled when reporters asked about Black's comments. Black was similarly surprised when reporters happened upon him outside a later McCain fundraiser. Speaking quietly, Black read from handwritten notes. "I deeply regret the comments. They were inappropriate. I recognize that John McCain has devoted his entire adult life to protecting his country and placing its security before every other consideration," Black said. Black repeatedly has argued that McCain - a former Navy pilot and Vietnam prisoner of war who has traveled the globe while serving in Congress - benefits any time national security matters are the news of the day. By contrast, Obama has less than four years experience in the Senate and has paid only one visit to Iraq. He plans a second trip before the November election. During the 2004 presidential race, President Bush, Vice President Dick Cheney and other Republicans argued that Democratic nominee John Kerry was soft on terrorism; the argument resonated with voters. The GOP also questioned the Democrats' record on national security in 2002, with White House political adviser Karl Rove saying Republicans should not shy away from citing terrorism concerns as a reason to vote for their party. The approach also paid dividends at the polls during that year's congressional elections. The GOP line - that Democrats had a pre-Sept. 11 mind-set - failed in the 2006 midterm elections as Democrats wrested control of Congress from the Republicans. More recently, former White House press secretary Scott McClellan wrote in a memoir that during the run-up to the 2003 invasion of Iraq, Bush and his team tried to make the weapons of mass destruction "threat and the Iraqi connection to terrorism appear just a little more certain, a little less questionable than they were." For his part, McCain has tried to portray Obama as naive on national security and foreign policy. On Monday, McCain told reporters he was stunned that Obama has never been briefed by Gen. David Petraeus, who is leading US forces in Iraq, yet Obama is calling for a US troop withdrawal. "Remarkable how someone can make an assessment of the situation without asking for a briefing from the commanding general," McCain said.