WASHINGTON - Sen. Barack Obama acknowledged Sunday he was considering a run for president in 2008, backing off previous statements that he would not do so.

The Illinois Democrat said he could no longer stand by the statements he made after his 2004 election and earlier this year that he would serve a full six-year term in Congress. He said he would not make a decision until after the Nov. 7 elections.

"That was how I was thinking at that time," said Obama, when asked on NBC's "Meet the Press" about his previous statements.

"Given the responses that I've been getting over the last several months, I have thought about the possibility" although not with the seriousness or depth required, he said. "My main focus right now is in the '06. ... After November 7, I'll sit down, I'll sit down and consider, and if at some point I change my mind, I will make a public announcement and everybody will be able to go at me."

Obama was largely unknown outside Illinois when he burst onto the national scene with a widely acclaimed address at the 2004 Democratic National Convention.

In recent weeks, his political stock has been rising as a potentially viable centrist candidate for president in 2008 after former Virginia Gov. Mark Warner announced earlier this month that he was bowing out of the race.

In a recent issue of Time magazine, Obama's face fills the cover next to the headline, "Why Barack Obama Could Be The Next President." He is currently on a tour promoting his latest book, "The Audacity of Hope: Thoughts on Reclaiming the American Dream."

On Sunday, Obama dismissed notions that he might not be ready to run for president because of his limited experience in national politics. He agreed the job requires a "certain soberness and seriousness" and "can't be something you pursue on the basis of vanity and ambition."

"I'm not sure anyone is ready to be president before they're president," Obama said. "I trust the judgment of the American people.

"We have a long and rigorous process. Should I decide to run, if I ever did decide to run, I'll be confident that I'll be run through the paces pretty good," Obama said.