Senator John McCain delivers a speech at the Riley Center at Mississippi State University. - AP

WASHINGTON (AP):

John McCain began Monday to woo voters with his military legacy, a gambit by the all-but-certain Republican presidential nominee to define himself as the candidate who has national security experience lacking in his Democratic rivals.

Barack Obama and Hillary Rodham Clinton, meanwhile, were still consumed in an increasingly bruising fight to win the Demo-cratic nomination, a contest that some in the party feared would weaken its chance to regain the presidency.

McCain emerged victorious in the Republican nomination contest weeks ago. And with seven months remaining before the November general election, polls indicate a tight race with either Obama or Clinton.

McCain mentioned neither of his potential opponents in his speech Monday. Nor did he discuss the war in Iraq or the weakening economy and spike in home foreclosures - issues on which he will be hammered by either Democrat.

Instead, he portrayed himself as a patriot who was born into a family of American warriors devoted to honour, courage and duty.

"I am the son and grandson of admirals," McCain said. "They were my first heroes, and their respect for me has been one of the most lasting ambitions of my life. ... They showed me how to love my country, and that has made all the difference for me."

Ex-war prisoner

A prisoner of war in Vietnam at a time his own father commanded all US forces in the Pacific, McCain said, "He prayed on his knees every night for my safe return ... . Yet, when duty required it, he gave the order for B-52s to bomb Hanoi in close proximity to my prison."

The Arizona senator spoke at a restored opera house that is part of Mississippi State University, near a naval air field named after his grandfather.

Obama agreed that the tough campaign was healthy but frustrating before a crowd of about 20,000 at Pennsylvania State University.

"As this primary has gone on a little bit long, there have been people who've been voicing some frustration," Obama said.

Other Obama supporters who have echoed the view issued more emphatic assessments.

New Mexico Governor Bill Richardson on Sunday called Obama's lead all but insurmountable, while Massachusetts Senator John Kerry said the contest would be reaching "a point of judgement" very soon.