Lieberman said Gore showed courage, character and fairness in choosing him, breaking "this barrier in American history."

Vice President Gore compared their quest to the election of John F. Kennedy as the first Roman Catholic president in 1960. He said the Democrats made history then, and with Lieberman's nomination, will do it again, 40 years later.

The shirtsleeved running mates hugged and shared a high-five hand slap as they began their campaign together at a sunny, midday rally.

Their wives spoke first, Hadassah Lieberman talking of her parents' survival of Nazi concentration camps during World War II.

Then Gore presented his vice presidential choice to the crowd, many waving newly printed Gore-Lieberman campaign placards.

Each man in turn talked of the issues they shared in the Senate and since.

Lieberman borrowed a line from the 1988 campaign of George Bush, father of the Republican presidential nominee, converting it to a call to stick with the Democrats this time.

"If you have to change horses in midstream, doesn't it make sense to get the one that's going in the right direction?" he said. "I love that line," Lieberman said, grinning as he turned to Gore to slap hands.

The senator began with a personal invocation, "Dear Lord, maker of all miracles, I thank you for bringing me to this extraordinary moment in my life."

Then the first Jew chosen for a major party ticket thanked Gore "for making this miracle possible for me and breaking this barrier for the rest of America forever."

"You know, there are some people who might actually call Al Gore's selection of me an act of chutzpah," said Lieberman, using the Yiddish word for audacity.

Then he showed some of his own in scoffing at the GOP attempt to liken his positions to those of George W. Bush on some campaign issues.

"With all due respect, I think that's like saying the veterinarian and the taxidermist are in the same business because either way you get your dog back," Lieberman said.

He promised to work with Gore "to renew the moral center of this nation." That message of morality has been Lieberman's trademark; he was one of the first Democratic senators to publicly rebuke President Clinton in the Monica Lewinsky affair.

Lieberman called Gore "a man of family and a man of faith."

"He has never wavered in his responsibilities as a father, as a husband and, yes, as a servant of God Almighty," Lieberman said.

Though differences have been noted in their stances on some issues, Gore said the real gap is between them and the Republicans.

"It comes down to this -- Joe and I are fighting to see to it that our prosperity benefits working families and not just the few," Gore said.

He noted that the last time Democrats held a convention in Los Angeles, they nominated Kennedy and shattered a religious barrier.

"That year we voted with our hearts to tear down a mighty wall of division," said Gore. "We made history. And when we nominate Joe Lieberman for vice president, we will do it again."

One benefit the Democrats see in choosing Lieberman is in his reputation for moral stances, including his criticism of Clinton in the Monica Lewinsky affair.

Republicans quickly sought to find differences they can exploit between Gore and Lieberman, differences on issues like Social Security and school vouchers.

Lieberman found more similarities than differences.

"Al Gore and I have pretty much walked the same path and when we've had disagreements they've been good-faith disagreements, never disagreements that touch our values," said Lieberman.

With his selection, Gore picked a moderate Democrat from a reliably Democratic state. Most polls have shown Bush building a lead in the wake of the Republican National Convention, and Gore is hoping to seize attention and galvanize support heading into next week's Democratic convention.

Republicans have also sought to tie Gore to Clinton, particularly Clinton's relationship with a White House intern. Lieberman was one of the earliest and sharpest Democratic critics of Clinton's behavior.

He's also been a sharp critic of Clinton-Gore fund-raising tactics and has teamed up with conservative Republicans to criticize sex and violence in the entertainment industry.

Analysts were split on whether Gore's tactic would work, as Gore walks a tightrope facing every vice president running on his own -- breaking with the boss.

If Clinton was unhappy with the choice, there was no public evidence.

"I think it's wonderful," said Clinton. "He's been a wonderful friend to me."