Arizona Senator John McCain officially threw his hat into the ring Wednesday as the newest Republican contender for the 2008 U.S. presidential race.

Speaking in Portsmouth, N.H., McCain said his experience as a navy pilot, Vietnam PoW and four-term senator have all prepared him for the challenges of high office.

Senator John McCain, shown earlier in April, admitted Wednesday that the U.S. made mistakes in Iraq and went into the country unprepared, a mistake he has vowed never to repeat.
(Jae C. Hong/Associated Press)

"We face formidable challenges, but I'm not afraid of them. I'm prepared for them," he said.

Now 70, McCain would be the oldest first-term president in U.S. history, but he said his age is an advantage.

"I'm not the youngest candidate, but I am the most experienced," he said. "I know how to fight and how to make peace. I know who I am and what I want to do."

McCain's announcement confirmed lingering speculation that the veteran politician would look to succeed President George W. Bush. McCain lost the Republican nomination to Bush in 2000 and he has been actively campaigning in recent months.

However, his campaign for the Republican nomination has lost some momentum. Once considered the front-runner for the presidential nomination, some recent polls showed McCain has recently lost ground to former New York City mayor Rudy Giuliani.

McCain also took center stage as a pitchman for Bush's recent troop hike in Iraq, an unpopular cause that may have caused McCain's public support to wane.

Now closely linked with the increasingly unpopular Iraq conflict, McCain has chosen to embrace it but has taken on a more candid tone than the current commander-in-chief.

He admitted Wednesday that the United States has made mistakes in Iraq and went into the country unprepared, a mistake he has vowed never to repeat.

McCain also offered some scathing criticisms that seemed aimed at Giuliani and Bush, although he named no names.

McCain said the nation "won't accept that firemen and policemen are unable to communicate with each other in an emergency because they don't have the same radio frequency" — a problem that existed during the al-Qaeda attack in New York on Sept. 11, 2001.

He also made an allusion to the federal government's disorganized response to Hurricane Katrina in 2005.
 
"They won't accept government's failure to deliver bottled water to dehydrated babies or rescue the infirm from a hospital with no electricity," he said.

"I'm not running for president to be somebody, but to do something; to do the hard but necessary things not the easy and needless things," McCain said.

"I'm not running to leave our biggest problems to an unluckier generation of leaders, but to fix them now, and fix them well."

A number of people have already declared themselves as candidates for the Republican nomination, including Giuliani, former Massachusetts governor Mitt Romney, former Arkansas governor Mike Huckabee and Kansas Senator Sam Brownback.

Bush cannot run again because under U.S. law, people can only hold the presidency for two terms.

The Republicans will name their presidential candidate during their National Convention, scheduled for Sept. 1-4, 2008, in Minneapolis-St. Paul.

With files from the Associated Press