Phoenix - In a sign of continued weakness in his home state, an online poll shows Sen. John McCain trailing Sen. Barack Obama by 3-percentage points in Arizona. The poll also shows the candidacy of Liberterian Bob Barr is having a significant impact on McCain's campaign by siphoning off conservative voters nationwide.

The Arizona poll was part of nationwide Zogby International poll that put Obama ahead in total electoral votes with 273 to 160 for McCain. The poll found 11 states with 105 electoral votes too close to call -- including Arizona. McCain's campaign in June included Arizona among its list of swing states.

McCain not only faced problems with Independent voters, he is losing a small, but potentially lethal voting block of the GOP right to Barr. The former Republican congressman from Georgia is pulling just enough voters in many states to shift the balance to Obama. Whether this bloc will remain in Barr's camp on election day could determine the outcome.

"Barr is hurting McCain all across the country," said Fritz Wenzel, director of communications for Zogby.

The Zogby poll of 1,142 likely Arizona voters was conducted June 11-30, with a margin of error of plus or minus 3 percentage points. The survey found Obama leading in Arizona with 42 percent of the vote, followed by McCain with 39 percent. Barr had 7 percent, followed by Independent Ralph Nader with 2 percent. Five percent of the voters selected other candidates and 5 percent were undecided.

Wenzel said 16 percent of Arizona voters who described themselves as very conservative said they would vote for Barr, with 64 percent backing McCain. The double-digit defection to Barr signals further trouble ahead for Arizona's senior Senator.

"That's very dangerous for a Republican candidate," Wentzel said.