U.S. Republican presidential nominee John McCain received a key endorsement Wednesday from President George W. Bush, the man who thwarted his ambitions in a bitter GOP campaign eight years ago.

U.S. President George W. Bush, left, greets Republican presidential nominee-in-waiting John McCain at the White House in Washington on Wednesday.
(Ron Edmonds/Associated Press)

McCain, 71, surpassed the requisite 1,191 Republican delegates late Tuesday as voters in Ohio, Vermont, Rhode Island and Texas put him over the threshold, according to tallies by various media outlets.

In a joint appearance at the White House Rose Garden after a private lunch Wednesday, Bush praised McCain as "somebody who can make tough decisions and won't flinch in the face of danger."

"I've campaigned against him and I've campaigned with him," the president said. "John showed incredible courage, strength of character and perseverance in order to get to this moment, and that's exactly what we need in a president."

Bush has gone out of his way in recent weeks to defend the Arizona senator's conservative credentials to the party's right flank. White House press secretary Dana Perino said the two men's previous battles would not stand in the way of Bush backing McCain.

When asked whether an endorsement and future campaign appearances from a highly unpopular president would potentially hurt his White House bid, McCain said he was "privileged and proud" to receive whatever help Bush could provide. But he said he understood Bush "had a day job to keep" in the Oval Office.

"I appreciate his endorsement and I appreciate his service to our country," McCain said, adding he expected the president would be an obvious asset in his home state of Texas.

But Bush, who was at times testy with reporters during the appearance, downplayed his role, saying the focus would be on the Vietnam veteran's superb qualifications to lead a country during a time of war.

"I can help raise him money, and if he wants my pretty face standing by his side at one of these rallies, I'd be glad to show up," Bush said.

"They're not going to be voting for me. I've had my time in the Oval Office."

Crossed swords over tax cuts, torture ban

McCain, a Vietnam veteran who led early in the 2000 Republican presidential nomination contest until Bush staged a hard-fought and controversial comeback in South Carolina, has had an uneasy relationship with the president in subsequent years.

A vocal proponent of Saddam Hussein's removal, he criticized the White House over U.S. strategy in the aftermath of the Iraq invasion, while also clashing with the Bush administration over tax cuts and campaign finance reform.

McCain, who was tortured and subjected to numerous beatings during his five years as a prisoner of war in North Vietnam, was a leading figure in Congress calling for the White House to back a ban on torture. He has slammed the Bush administration's support for controversial interrogation techniques of terrorism suspects such as waterboarding, or simulated drowning.

The president made morning phone calls to McCain's former rivals Mike Huckabee, Mitt Romney and Fred Thompson to congratulate them on their primary campaigns. He intended to call Rudy Giuliani later in the day, Perino said.

"He said he appreciated their ability to keep their sense of humour and that he looks forward to working them in the '08 election," Perino said.

Republicans won't officially nominate McCain until early September at the Republican national convention in Minneapolis-St. Paul.

With files from the Associated Press