Senator John McCain, President Bush's bitter rival for the Republican nomination four years ago, is endorsing Mr. Bush's bid for another four-year term and praising his decision to go to war with Iraq.
On the first night of the four-day convention, Senator McCain praised Mr. Bush as a tested leader who will not yield in combating terrorism.
He also defended Mr. Bush's decision to go to war with Iraq, an issue on which public opinion polls say Americans are deeply divided. "I believe as strongly today as ever, the mission was necessary, achievable and noble," he said. "For his determination to undertake it, and for his unflagging resolve to see it through to a just end, President Bush deserves not only our support, but our admiration."
Despite his warm words, Mr. McCain has often been at odds with Mr. Bush on many issues, even questioning whether the administration has sent enough troops to Iraq to fulfill its mission. He also opposes the president's stand on abortion and tax cuts.
The maverick Republican has defended Mr. Bush's Democratic challenger, John Kerry, from attacks on the senator's Vietnam War record, including those from a group of pro-Republican veterans who accuse Mr. Kerry, in television advertisements, of lying about his combat experience.
Mr. McCain, a former prisoner of war in Vietnam, has called the ads dishonorable and dishonest, and urged Mr. Bush to condemn them.
But it is Mr. McCain's ability to appeal to independent voters and Democrats that prompted Mr. Bush to seek the senator's support for his campaign. That ability was apparent Monday night as Mr. McCain spoke:
"My friends in the Democratic Party, and I am fortunate to call many of them my friends, assure us they share the conviction that winning the war against terrorism is our government's most important obligation," he said. "I do not doubt their sincerity."
Monday's convention program was designed to highlight Mr. Bush's role as a war president.
An Iraqi immigrant, Zainab al-Suwaij, who fled the regime of Saddam Hussein 12 years ago, thanked Mr. Bush for toppling the Iraqi leader, and remembered the men and women who lost their lives in the mission.
"So as I grieve for the courageous Americans and Iraqis who were killed and injured during Iraq's liberation, I tell you proudly that their noble sacrifice was not in vain," she said. "As Iraqis assume full sovereignty, they embrace the American people in friendship and gratitude. I promise you, we will never forget what your sons and daughters did for us."
Former New York City Police Commissioner Bernard Kerik also spoke to the convention. Mr. Kerik who was in office on September 11, 2001, when the city came under the worst terrorist attack in the nation's history, and who trained Iraqi police in Baghdad last year, paid tribute to Mr. Bush's leadership in the war on terror and in Iraq.