WASHINGTON — Democrat Barack Obama begins the presidential campaign with some overwhelming advantages over Republican John McCain, a USA Today/Gallup Poll finds, but voters also express doubts about the Illinois senator's experience and ability to be the commander in chief.

A 54 percent majority of those surveyed are concerned Obama lacks the experience to be an effective president. A similar number say he "may be too closely aligned with people who hold radical political views."

Still, the nationwide poll gives Obama an edge of 6 percentage points over McCain among likely voters, 50 percent-44 percent. That's almost precisely where the race stood in the USA Today poll taken just before Obama clinched the Democratic nomination on June 3.

Among registered voters, Obama leads McCain 48 percent to 42 percent.

"Obama is the favorite because of the conditions that are prevailing, but he's not a heavy favorite because of his personal liabilities," says political scientist Larry Sabato, director of the University of Virginia's Center for Politics. "One is completely legitimate, which is experience, and the other is completely illegitimate, which is race."

The political landscape overwhelmingly favors Obama:

On issues, voters are most concerned about energy and the economy, and they prefer Obama by a double-digit margin on each. He's favored on taxes, traditionally a Republican strength, and essentially tied with McCain on handling illegal immigration.

On personal characteristics, McCain is rated more highly than Obama in just one of 10 categories — as a "strong and decisive leader." Obama swamps his opponent as someone who is empathetic and independent and "understands the problems Americans face in their daily lives."

What's more, McCain is saddled with one of the most unpopular presidents of modern times. Two-thirds of voters say they are concerned that McCain would pursue policies too similar to those of President Bush, whose job-approval rating is 28 percent.

Yet the Arizona senator remains competitive, both because of trust in his ability to keep the country safe and questions about Obama. The sole issue on which McCain clearly is favored is terrorism — still an important concern, albeit overshadowed by the economy.