In an effort to ensure they are not completely shut out of the spotlight, Democrats are mobilizing an aggressive counterattack to the Republican message that will take center stage during next week’s convention.

The chairman of the Democratic National Committee, Terry McAuliffe, said yesterday the party has launched an advertising blitz in 21 battleground states and that it would be opening a Manhattan convention headquarters Friday.

The Democrats’ weeklong operation will be led by Governor Vilsack of Iowa under the theme “Mission Not Accomplished,” a take-off on the “Mission Accomplished” slogan used by President Bush when he declared an end to major combat in Iraq in April 2003 during a speech aboard the aircraft carrier USS Lincoln. Senators Schumer and Clinton and Rep. Charles Rangel are also expected to play key roles in the counterattack, in much the same way Mayor Giuliani, a Republican, did during the Democratic convention in Boston.

The goal, Mr. McAuliffe told reporters, is to provide a constant stream of responses to the Republican-dominated week.

“Every day next week we will be highlighting the simple truth about the administration of George Bush: mission not accomplished,” Mr. McAuliffe said during a phone conference. “We are going to have events everywhere, from Grant’s Tomb to Madison Square Garden.”

Mr. McAuliffe said the Bush administration has failed Americans on such issues as health-care reform, the economy, jobs, and the war in Iraq, and had increased the country’s reliance on Middle East oil, squandered an opportunity to build international alliances, and favored special-interest groups over the public good.

“Four years ago he said he would make health care more affordable, but today health insurance premiums are up by 50%, we have a prescription plan that helps the drug company profits but not American seniors, and patients are prohibited from buying cheaper prescription drugs from Canada,” the DNC chairman said.

The strategy is a departure from the Democratic Party’s usual approach, which has been regarded by many as disorganized and not hard-hitting enough to dent public opinion. The Republicans, meanwhile, have had an around-the-clock war-room-type operation to blanket the press with responses to Senator Kerry’s moves for months.

“It’s a shift,” said a Democratic political strategist, Hank Sheinkopf. “They don’t want to be out-organized by the Republicans. They have no choice and they are doing the right thing. This is a very close election.”

A former executive director of the New York Republican State Committee, Brendan Quinn, said Democrats were “taking one out of the Republican playbook,” a move he deemed “desperate.”

“The Republican Party and the Bush administration have a consistent message and a consistent strategy,” he said. “The Kerry campaign is trying to find something that resonates with the American people, but their views do not represent Middle America.”

Speeches by Mayor Bloomberg, Mr. Giuliani, and Senator McCain will undoubtedly overshadow protesters and dissenting voices, Mr. Quinn predicted.

Mr. McAuliffe called the convention a “masquerade ball” designed to put a moderate face on the president’s far more conservative agenda.

Mr. McAuliffe went to pains to distance himself from the protesters, saying they had no ties to the Democratic Party.

The chairman also denied criticisms that Mr. Kerry had failed to adequately define his own positions and ideas for reform, saying the Massachusetts senator had just outlined a plan to create 10 million new jobs, to reduce health-care premiums by 10%, and to provide tax credits to families sending their children to college.

The Bush administration did hang back during the Boston convention, as is generally tradition. It’s yet to be seen whether Mr. Kerry will himself take an aggressive line against the Republicans during their convention.