WASHINGTON - President Bush yesterday stood beside John McCain in the White House Rose Garden and offered an effusive endorsement of his onetime rival's candidacy to succeed him, declaring that the Arizona senator "will bring determination to defeat an enemy and a heart big enough to love those who hurt."

In a jocular reference to his own low standing in the polls, Bush pledged to do whatever he could to help McCain win the election - be it campaigning alongside McCain or instead saying "I'm against him."

But McCain - who clinched the Republican nomination for president on Tuesday with wins in Texas, Ohio, Vermont, and Rhode Island - dismissed any notion that he would seek to distance himself from Bush.

McCain said he had "great admiration, respect, and affection" for Bush and welcomed the president's help both in fund-raising and on the campaign trail.

McCain said he wanted to have as many campaign events together with Bush as "the president's heavy schedule" allowed. "And I look forward to that opportunity," he added. "I look forward to the chance to bring our message to America."

Indeed, while Bush and McCain famously clashed during the 2000 Republican primary and since then on such issues as campaign finance reform, harsh interrogation techniques, and tax cuts, the two Republican leaders yesterday underscored an issue in which their policy message is identical: The US military should not withdraw from Iraq or shrink from fighting terrorism.

"The good news about our candidate is he'll be a new president, a man of character and courage, but he's not going to change when it comes to taking on the enemy," Bush said.

"He understands this is a dangerous world. And I understand we'd better have steadfast leadership, [someone] who's got the courage and determination to pursue this enemy, so as to protect America."

Stephen Hess, a political analyst at the nonpartisan Brookings Institution, said that Bush's effusive endorsement of McCain was in part a recognition by the president that his party had nominated the Republican candidate who may represent the best chance that Bush's policy in Iraq will continue past 2009.

McCain "supports the Iraq policy to the fullest and has the most authority in doing it, so strangely - given their history - [Tuesday] night symbolically was very good news for George W. Bush," Hess said.

"Bush is getting the very best GOP candidate he had any right to expect. . . . He can thank his lucky stars he's got McCain around, and that is what today represented."

And while McCain has been critical of Bush's approach to the interrogation of suspected terrorists, Bush made clear that he sees McCain's election as the best chance of continuing his broader approach to the war on terrorism.