Former New York Mayor Rudy Giuliani, who dropped out of the Republican race early and quickly endorsed McCain after a disappointing finish in the Florida primary, reminded Americans of the dangers the country faces.
Giuliani focused on his friend McCain's experience on national security and foreign affairs, contrasting it with Obama's experience and judgment.
"No one can look at John McCain and say that he is not ready to be commander in chief," Giuliani said.
Obama, the former mayor said, has "never run a city, never run a state, never run a business. He's never had to lead people in crisis. This is not a personal attack ... it's a statement of fact. Barack Obama has never led anything. Nothing. Nada."
Giuliani charged the Democratic Party with being "in a state of denial about the threat that faces us now and in the future," compared to McCain who will "keep us on offense against terrorism at home and abroad.
"To those Americans who still feel torn in this election, I'd like to suggest one way to think about the choice you have to make in 2008: You're hiring someone to do a job -- an important job that involves the safety and security of your family," Giuliani said.
"Gov. Palin represents a new generation," he said. "She's already one of the most successful governors in America -- and the most popular. And she already has more executive experience than the entire Democratic ticket. She's led a city and a state. She's reduced taxes and government spending. And she's actually done something about moving America toward energy independence -- taking on the oil companies while encouraging more energy exploration here at home. Taxpayers have an advocate in Sarah Palin. She even sold the former governor's private plane on eBay."
Romney, believed to be angling for a future presidential run, also gave a full-throated endorsement of his former primary rival.
"We need change all right -- change from a liberal Washington to a conservative Washington. We have a prescription for every American who wants change in Washington -- throw out the big-government liberals and elect John McCain," Romney said as the crowd cheered "USA! USA!"
"At [a faith-based forum at] Saddleback [Church], after Barack Obama dodged and ducked every direct question, John McCain hit the nail on the head: Radical Islam is evil, and he will defeat it. Republicans prefer straight talk to politically correct talk," Romney said.
Taking a veiled jab at Michelle Obama for suggesting on the campaign trail in February that she was "proud" of the country for the first time in her life after her husband won the Iowa caucuses, Romney said, "Just like you, there has never been a day when I was not proud to be an American."
Huckabee, a former Baptist minister who, thanks to widespread support from Christian evangelicals, was the last of McCain's most credible rivals to drop out of the race, reminded the crowd he wanted to be at the top of the GOP ticket.
"As much as I appreciate the opportunity to speak tonight, I really was originally hoping for the slot on Thursday called the acceptance speech," Huckabee said. "But I am delighted to speak on behalf of my second choice for the Republican nomination for president, John McCain -- a man with the character and stubborn kind of integrity that I want in a president."