US President George W. Bush praised John McCain's "independence and character" in a brief Republican National Convention speech designed to offer some distance between the unpopular president and his would-be successor. Bush's address, delivered via satellite link from the White House, marked a significantly diminished role from earlier plans to have the president address the convention Monday in the prestigious final speaker slot. Bush lauded McCain as Republicans tried to put their national convention back on track after the distractions of Hurricane Gustav and jarring disclosures about vice presidential candidate Sarah Palin. A larger-than-life image of Bush speaking from the White House was seen on the convention floor, projected in a way that made it appear as if Bush actually were on the stage. Bush praised McCain as an "independent man who thinks for himself." Bush had canceled his original speech plans to be closer to hurricane preparations. The party eventually scrapped most of its first-day activities as well. The storm proved less devastating than had been feared, and Republicans scrambled to revive a convention aimed at convincing Americans that McCain, a veteran senator, has the wisdom and experience to guide the United States through uncertain times, and Democratic rival Barack Obama does not. In addition to Bush, Tuesday's speakers included Joe Lieberman, who was the Democrats' vice presidential candidate in 2000, and former senator and television star Fred Thompson, who briefly sought the Republican nomination this year. Bush's support is a mixed blessing for McCain. The president retains the loyalty of Republican stalwarts, many of whom have been unenthusiastic about McCain. But Bush's overall popularity fell three years ago after his administration's botched handling of devastating Hurricane Katrina. It has been dragged down further by the Iraq war. Bush's cameo appearance was highly unusual for a two-term president addressing his party's convention as he prepared to leave office. Asked if convention planners said Bush should not come, White House press secretary Dana Perino said, "I wouldn't put it that way. We were in touch with them, and we were trying to figure out what would work best for them and what would work best for the president." In his remarks, Bush reprised national security themes that propelled him to re-election in 2004. "We need a president who understands the lessons of September 11, 2001: That to protect America, we must stay on the offense, stop attacks before they happen, and not wait to be hit again. The man we need is John McCain." Obama's campaign, which has sought to link McCain to Bush, was quick with a response. It said Bush "enthusiastically passed the torch to the man who's earned it" by supporting the president's policies. Obama has kept a low profile this week, spending Tuesday out of public sight. He met with campaign aides and received his first national security briefing as a nominee, conducted at the FBI's office in Chicago. Republicans hoped a strong convention would help McCain offset the boost Obama received from last week's Democratic convention in Denver. A new Gallup poll showed Obama with a 50 percent to 42 percent lead. The race had been even before the conventions. Much of the media attention Tuesday remained fixed on Palin, the little-known Alaska governor chosen by McCain as his running mate. On Monday, Palin announced that her unmarried 17-year-old daughter, Bristol, was pregnant. It also was revealed that an attorney had been hired to represent Palin in an Alaska state ethics investigation. Also, a watchdog group released details of extensive funding requests Palin had made to the federal government, undermining McCain's claims that she is a force against wasteful government spending. The revelations, among others, raised questions about whether Palin's background was fully explored before she was picked. McCain, touring a fire house in Philadelphia, Pennsylvania, said "The vetting process was completely thorough, and I'm grateful for the results." There were indications that Republicans thought they could turn Palin-related controversy to McCain's gain. Officials said Levi Johnston, 18-year-old father of the baby Bristol Palin is expecting, was en route to the convention from his home in Alaska. Vice presidential choices usually are not big factors in presidential races and, with Palin drawing strong support from the important Christian conservative base, McCain is not expected to pull her from the ticket. Palin has drawn extra scrutiny because McCain is a cancer survivor and, at 72, would be the oldest first-term president in US history. Palin has no foreign affairs experience and has served less than two years as governor. The attention given to Palin distracted from the messages Republicans sought to present to a national television audience highlighting McCain's background as a former Vietnam prisoner of war, his hawkish stances on national security and his calls to cut taxes and expand oil exploration. Bush referred to the years of torture McCain endured in a prisoner-of-war camp. "If the Hanoi Hilton could not break John McCain's resolve to do what is best for his country, you can be sure the angry left never will," he said. Lieberman pressed a theme central to the campaign: that McCain has shown political courage, especially in risking his presidential bid by making an unpopular call to increase US troops "When others wanted to retreat in defeat from the field of battle, when Barack Obama was voting to cut off funding for our troops on the ground, John McCain had the courage to stand against the tide of public opinion," Lieberman said in excerpts released in advance of his speech. Lieberman, an independent, is one of McCain's closest allies and had been considered as a vice presidential pick. He angered many Democrats for supporting Bush's policies in the Iraq war and backing McCain. Thompson, a former star of the popular "Law & Order" crime series, praised McCain's character and honor. "It's pretty clear there are two questions that we'll never have to ask ourselves: `Who is this man?' and `Can we trust this man with the presidency'?" he said. Thompson also defended Palin, saying she is "from a small town, with small town values, but apparently that's not good enough for those folks who are out there now attacking her and her family." The schedule calls for former New York Mayor Rudy Giuliani to give the convention's keynote speech Wednesday, the same evening delegates deliver the party's nominations to McCain and Palin. Palin will address the convention Wednesday; McCain delivers his acceptance speech Thursday.