OXFORD, Miss. — John McCain accused Barack Obama of compiling "the most liberal voting record in the United States Senate" Friday night as the two rivals clashed over taxes, spending, the war in Iraq and more in an intense first debate of the White House campaign. "Mostly that's just me opposing George Bush's wrong-headed policies," shot back the Democrat.

Obama said his Republican rival has been a loyal supporter of the unpopular president across the past eight years, adding that the current economic crisis is "a final verdict on eight years of failed economic policies promoted by President Bush and supported by Sen. McCain."

The two men were polite but pointed as they debated at close quarters for 90 minutes on the University of Mississippi campus.

McCain accused his younger rival of an "incredible thing of voting to cut off funds for troops in Iraq and Afghanistan," a reference to legislation that cleared the Senate more than a year ago.

Obama disputed that, saying he had opposed funding in a bill that presented a "blank check" to the Pentagon while McCain had opposed money in legislation that included a timetable for troop withdrawal.

Obama opposed the invasion of Iraq in 2002, before he was a member of Congress, while McCain voted in the Senate to authorize the war.

"You were wrong" on Iraq, Obama repeated three times in succession. "John, you like to pretend the war began in 2007."

McCain replied that Obama has refused to acknowledge the success of the troop buildup in Iraq that McCain recommended and Bush announced more than a year ago.

The two presidential candidates stood behind identical wooden lecterns on stage at the performing arts center at the University of Mississippi for the first of three scheduled debates with less than six weeks remaining until Election Day. The two vice presidential candidates will meet next week for their only debate.

The 47-year-old Obama is seeking to become the nation's first black president. McCain, 72, is hoping to become the oldest first-term chief executive in history — and he made a few jokes at his own expense.

"I've been around a while," he said at one point. "Were you afraid I couldn't hear him?" he said at another after moderator Jim Lehrer repeated a phrase.

But he also sought to turn his age into an advantage. "There are some advantages to experience and knowledge and judgment," he said. "And I honestly don't believe that Sen. Obama has the knowledge or experience" to serve as commander in chief.