Sen. John Kerry is facing his first primary opponent since he first took office 23 years ago, and his challenger has one issue in mind: The Massachusetts senator's 2003 vote authorizing President George W. Bush to launch military action against Iraq, according to AP. Ed O'Reilly said he was so incensed by Kerry's vote that he gave up his law practice to devote himself full-time to ousting the Democratic 2004 presidential nominee from office. «I looked at that and said 'What kind of person would vote for a war knowing it's wrong?»' said O'Reilly, who supported Kerry's 2004 presidential bid. «John Kerry knew the vote was wrong but to increase his chances to become president he voted for it anyway. It was a calculated vote based on his own political ambition.» Kerry has defended his vote, saying it was intended to give Bush a strong hand in seeking international sanctions _ an option he says the White House did not pursue effectively. Although few give O'Reilly anything more than long shot odds at defeating Kerry, the 55-year-old lawyer and former firefighter from the fishing village of Gloucester, Massachusetts, has already scored one victory. Earlier this month, O'Reilly received the backing of about 23 percent of delegates at the annual state Democratic convention _ despite an effort by Kerry supporters to deny him the 15 percent needed to get a spot on the ballot. «John Kerry and his campaign worked so hard from the top down in order to squelch my candidacy and I still came out with nearly one out of four of the party insiders,» he said. «That says a lot about how people feel about John Kerry.» A recent poll found 51 percent of people who have voted in previous general elections said it's time to give someone other than Kerry a chance, while 38 percent said the senator deserves to be re-elected. Nine percent were undecided, and 2 percent didn't respond. The Suffolk University/WHDH-TV poll of 500 Massachusetts voters was conducted during June 8-10 and had a margin of error of plus or minus 4.4 percentage points.