Sen. Joseph Lieberman, once an avowed Democrat, called McCain the best choice to lead the country because he can reach across party lines in accomplishing good for his country.
Click play to hear excerpts from Lieberman's speech, plus more insight from CBN News Reporter Paul Strand, from the convention floor.
"I'm here tonight because John McCain is the best choice to bring our country together and lead our country forward," the Connecticut senator said Tuesday night. Lieberman took the prime spot at the Republican National Convention to endorse his long-time friend and colleague in the Senate. Click here to watch Sen. Lieberman's entire speech.
"I'm here because John McCain's whole life testifies to a great truth: being a Democrat or a Republican is important. But it is not more important than being an American," he said.
Lieberman, who left his party during the last election cycle to keep his seat in the senate, urged Americans from all parties to work together.
"What matters is certainly not whether we are Democrats or Republicans, but that we are all Americans," he said. He highlighted how natural disasters like Hurricane Gustav brings people together to accomplish good.
"The truth is, it shouldn't take a hurricane to bring us together like this," he said. "It shouldn't take a natural disaster to teach us that the American people don't care much if you have an "R" or a "D" after your name."
Lieberman noted that Democratic candidate Barack Obama's record in the Senate did not match that of McCain's in reaching across party lines.
"Sen. Obama is a gifted and eloquent young man who can do great things for our country in the years ahead. But eloquence is no substitute for a record - not in these tough times," he said.
"In the Senate he has not reached across party lines to get anything significant done, nor has he been willing to take on powerful interest groups in the Democratic Party." Lieberman added.
Lieberman also took aim at Obama for his voting record on troop funding and Bush's troop surge last year that proved effective in curtailling violence in the region.
"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.
"Because of that, today, our troops are at last beginning to come home, not in failure, but in honor," Lieberman said
In 2007, Obama voted against money for troops in Iraq and Afghanistan, but the bill passed overwhelmingly. Obama did vote in favor of troop funding in April, but the measure included a call to pull troops out of Iraq immediately. President Bush vetoed that legislation.
Eight years ago, Lieberman stood before the Democratic National Convention in Los Angeles to accept the nomination as Al Gore's running mate.
His address Tuesday was originally scheduled for opening night, but was cut in a dramatic scaling back of the convention because of Hurricane Gustav.
Sources: CBN News, The Associated Press