BOSTON — Republicans called on some of the most potent critics of Sen. John Kerry on Thursday to argue on his big night that the Democratic presidential nominee is unfit to lead the country in a time of war.

Republican national Chairman Ed Gillespie said the Bush campaign will now begin spelling out more details of a second Bush term.

"The next four weeks will be about the next four years," Gillespie said late Thursday. And he said the Republican National Committee will begin spending money on campaign ads.

Gillespie said Kerry's speech was a lost opportunity to clarify his position on Iraq. He said the Democrat's criticism of President Bush for "misleading" the country into war is at odds with Kerry's statements prior to his October 2002 vote authorizing the use of force in Iraq.

"If candidate Kerry was misled, he was misled by Senator Kerry," Gillespie said.

Earlier in the day, former New York Mayor Rudy Giuliani, former Massachusetts Gov. William Weld and Democratic Sen. Zell Miller of Georgia led the attacks on Kerry on the night he's accepted his party's presidential nomination and gave a speech that could be crucial to his bid.

At a news conference in Boston, Giuliani pointed to Kerry's vote in October 2002 to authorize the use of force in Iraq, coupled with his vote a year later against $87 billion for the troops and reconstruction efforts in Iraq and Afghanistan.

"Nothing could tell you more about John Kerry than this quote: 'I voted for the appropriation before I voted against it,' " Giuliani said, slapping his forehead in mock disbelief. "Does that tell you everything you need to know about John Kerry?"

Miller, a Democrat who has backed the Bush re-election effort for months, said Kerry's convention performance is like a magic act.

"Somewhere, David Copperfield must be green with envy," Miller said in a conference call, referring to the Democrats' efforts to transform Kerry's image. "We're watching him try to do an extreme makeover right before our eyes. We don't know what he's going to say next."

Another Republican at the Boston news conference was Weld, the former Massachusetts governor who ran a tough Senate race against Kerry in 1996, finally losing by 7 percentage points.

Weld cautioned Kerry is as elusive in a debate format as he has been on the national talk shows.

"He is an international grandmaster at the art of changing the subject," Weld said. "There is nobody better at that than Senator Kerry, he's got the speed of a welterweight."

But Weld said the advantage Kerry had in his Senate election eight years ago was a byproduct of the national election mood that year.

"The Massachusetts race that year got nationalized, people started focusing on Newt Gingrich and Jesse Helms at the end of the race, which made it tough for the Republicans in Massachusetts," Weld said.

Kerry campaign aides dismissed the Republican attacks, saying the GOP is "scared" by Kerry's White House bid.

"They're trying to pull out all the stops to get in the way of Senator Kerry introducing himself to voters," said Kerry spokesman Phil Singer.

Democrats at the convention are avoiding discussion about Kerry's record, Giuliani said.

"We're going to run on President Bush's record, we're not going to run away from it, which is what they've been doing for the last four nights," said Giuliani.