By Steve Holland
WASHINGTON (Reuters) - U.S. Senator John McCain of Arizona, declaring "I've got a lot of energy left in me," announced plans on Tuesday to seek a sixth term in office in 2016.
McCain, the Republican presidential nominee in 2008 and now the powerful chairman of the Senate Armed Services Committee, vowed to face down any challenger.
He had defeated a strong challenge from a tea party conservative candidate in 2010 in the Republican primary election and coasted to re-election over a Democratic opponent.
"I think you have to be prepared for any challenge," he told Reuters in a telephone interview from Arizona. "I'll be ready for anything, both right, left and Democrat as well."
McCain, the senior senator in the Republican-dominated southwestern state, formally announced his long-expected plans at an Arizona Chamber of Commerce & Industry event in Phoenix.
The 78-year-old McCain, who was first elected to the U.S. Senate in 1986, said he is ready to combat tough foreign and domestic challenges.
"No success in my life has ever come without a good fight, and there is so much worth fighting for today," he told an enthusiastic crowd. "I'm eager to get started and ready for whatever comes."
Speaking to Reuters, McCain said the twin threats of Iran and Islamic State militants represent the biggest national security challenges to the United States. He disagreed with President Barack Obama's handling of both threats, saying the president has been "leading from behind."Saying the world is in the worst turmoil since the end of World War Two, McCain declared: "I've got a lot of energy left in me to try to address this great challenge to our nation and its security."
He said a top priority for him on the Senate Armed Services Committee is to lift so-called budget sequestration policies that have capped military spending.
The Vietnam War veteran, who was a prisoner of war, has been a prominent voice on foreign policy issues. In 2008, he ran for the White House unsuccessfully against Democratic U.S. Senator Barack Obama.
The Republican senator has been known for his willingness at times to work across party lines.
Last year, at a meeting of the Arizona Republican Party, a resolution passed by a voice vote that censured McCain for what his critics called his overly liberal record. It was a sign of continued distrust of him by some conservatives in the state.
(Additional reporting by David Schwartz in Phoenix and Curtis Skinner in San Francisco; editing by Alex Dobuzinskis, Sandra Maler and Bernard Orr)