NEW YORK – In a passionate address Thursday night that brought tears to the eyes of some delegates, President Bush pledged to build a safer world and a more hopeful America as he formally accepted his party’s nomination for a second four-year term.

The president also picked apart Democratic Sen. John Kerry’s record on the Iraq war and tax cuts and summoned the nation toward victory over terrorism and economic security at home.

“Nothing will hold us back,” he said in a Republican National Convention acceptance speech that launched his fall re-election campaign.

“We are staying on the offensive – striking terrorists abroad – so we do not have to face them here at home,” Bush said in a prime-time address not far from ground zero of the Sept. 11, 2001, terrorist attacks.

“And we will prevail.”

“Four more years, four more years,” the delegates yelled as Bush strode – alone – onto a podium in the middle of a packed convention hall. His introduction was a video that stirred memories of Sept. 11 – and credited him with having “the heart of a president.”

Bush’s speech marked the beginning of a two-month sprint to Election Day, and Kerry clearly couldn’t wait. In a ferocious counterattack after a week of GOP convention-week criticism, he called the wartime commander in chief and Vice President Dick Cheney unfit to lead the nation.

“I’m not going to have my commitment to defend this country questioned by those who have refused to serve when they could have and by those who have misled the nation into Iraq,” he said in remarks prepared for a midnight campaign appearance in Ohio.

Kerry won five military medals in the Vietnam War; Bush was stateside in the National Guard and Cheney’s five draft-era deferments kept him out of the service.

The Bush-Cheney campaign readied a new general election advertising campaign to build on elements in his convention speech. In the commercials, Bush vows to “spread ownership and opportunity,” “make our economy more job-friendly” and help lower health care costs.

Invoking the name of God several times during the hour-long presentation, President Bush also promised to continue his “compassionate conservative philosophy.”

“Government should help people improve their lives, not try to run their lives,” he said. “I believe this nation wants steady, consistent, principled leadership and that is why with your help we will win this election.”

Maine’s GOP delegates leaped to their feet in an enthusiastic response to the president’s message.

“I thought he was fabulous,” said Kevin Raye, a delegate from Perry. “He hit a home run tonight – in every sense of the phrase. I just couldn’t be more thrilled.”

Locked in a tight race, the president underscored his differences with Kerry on issues of war, tax cuts, values and more. At the same time, he used terms less incendiary than those wielded by Cheney or Sen. Zell Miller, D-Ga., from the convention podium Wednesday night.

Bush said Kerry and Democratic vice presidential candidate John Edwards both had voted against $87 billion in aid for “troops doing battle in Afghanistan and Iraq.”

The president said Kerry has proposed “more than $2 trillion in new federal spending so far, and that’s a lot, even for a senator from Massachusetts.”

Bush added: “To pay for that spending, he is running on a platform of increasing taxes – and that’s the kind of a promise a politician usually keeps.”

Contrary to Bush’s characterization, Kerry’s economic plan calls for rolling back the Bush-era tax cuts only on the top 2 percent of wage-earners, while leaving the rest in effect.

The public opinion polls made the race a toss-up as Bush stepped to a custom-made, theater-in-the-round style podium at Madison Square Garden, the country divided along political lines that shaped the Electoral College strategy for him and Kerry alike.

By all accounts, Bush is safely ahead in customary GOP strongholds across the South and Great Plains states, with Kerry similarly situated in Democratic base states from New York to Illinois to California.

That left about 20 states to contest across nine weeks of personal campaigning, presidential and vice presidential debates and more than $100 million in campaign advertising – the White House the prize.

Bush offered Reagan-style optimism in a time of national testing, mixed with self-deprecating humor.

“Some folks look at me and see a certain swagger which in Texas we call ‘walking,”‘ he joked.

Former Maine Gov. John R. McKernan said the president clearly demonstrated not only his strength and his resolve, but also his sense of humanity.

“That’s the combination of qualities that, for those of us who know him, we have come to respect and we know that he’s the kind of leader America needs,” McKernan said.

McKernan, a former 1st District congressman; his wife, Sen. Olympia Snowe, and Sen. Susan Collins were among the first national political figures to endorse George W. Bush’s run for the presidency in 2000. Snowe said the president delivered a “very powerful message about the future” that correctly identified the issues that must be addressed over the next four years.

“He’s laid the groundwork in his speech tonight, and he will hopefully build upon it in the next two months during the course of the campaign,” she said.

Collins said the president offered the American people a “terrific” vision of the future, demonstrating an understanding that today’s problems will not be solved with solutions from the past.

“He also demonstrated how important his role of commander in chief has been,” Collins said. “He’s energized this crowd. We’re all going to go back home and work harder than ever.”

But Maine’s delegation, which is largely moderate on social issues, sat quietly as other delegates cheered wildly when the president reaffirmed his opposition to abortion.

“Because we are a caring society who values its weakest members, we must make a place for the unborn child,” he said.

Still, delegates such as Jim Donnelly of Presque Isle said the president did an exemplary job of laying out his domestic agenda for critics who claimed the former Texas governor had no plan whatsoever. He said the president also gave the delegates a sense of direction for United States intervention in Iraq.

“He just spelled it out for the American people and gave them a true sense of where we are at this point in our struggle with the terrorists and for the future.”

Bush pledged a second-term effort to reform and simplify the tax code, part of a broader effort to appeal to millions of Americans anxious over the economic security of their families.

In a return to the rhetoric of compassionate conservatism that marked his 2000 election campaign, the Republican pledged changes in health coverage, pensions and more. He renewed his call for an overhaul of Social Security that would allow individuals to invest some of their payroll taxes on their own.

He also said he would double the number of individuals eligible for the government’s main job-training program and create American “opportunity zones” that offer tax relief and other incentives to new businesses.

He outlined plans for steps that he has had trouble pushing through a divided Congress – changes in comp time and flex time legislation opposed by organized labor, many Democrats and some moderate Republicans, and caps on medical malpractice awards bitterly resisted by the trial lawyers, political benefactors of Democrats.

The Associated Press contributed to this report.