NEW YORK – Ground zero.

The two words immediately trigger the graphic image of the burning twin towers at the World Trade Center and have been a persistent theme in most of the speeches delivered at the Republican National Convention this week.

As President Bush returned Thursday to the city that helped define his presidency, many New Yorkers were reminded of the siegelike atmosphere that followed the terrorist attacks three years ago. This week, armies of New York Police Department officers cordoned off the streets with barricades to protect delegates from demonstrators. Wearing body armor and toting M-16 automatic weapons, they guarded the entrances to the swankiest hotels.

Various speakers made impassioned references to the WTC attack this week. They said it was an assault that must be answered, that those who died must be avenged and never forgotten.

With such constant reminders of the tragedy, Maine GOP delegate Jim Donnelly of Brewer decided Thursday to take one more look at the gaping expanse in the middle of Manhattan where once were the tallest buildings in the nation. Joined by Kathleen Newman of Hallowell and Abby Holman of Fayette, both guests of the Maine Republican delegation, Donnelly stood quietly behind a towering fence erected around the site where new construction is under way.

The three Mainers exuded the same depth of quiet respect one might associate with the changing of the guard ceremony at the Tomb of the Unknown Soldier in Washington. They seemed oblivious to the crowds that milled around them.

A Brooklyn native, Donnelly said he had family members who worked in and around the World Trade Center on Sept. 11, 2001. None was injured, but several family friends died.

“It’s like sacred ground,” Donnelly said as he surveyed the massive footprint of where the buildings once stood. “This is the resting place for a lot of folks. It’s a stark reminder of our vulnerability and why the president has taken the actions that he has around the world today.”

It was the second trip to the site for Newman, and she was impressed at how much had been accomplished by workers since her first visit in April.

“The Republican National Convention came to New York to show the city officials that we have faith in them and their ability to get themselves back on their feet,” she said. “Seeing all of this progress is encouraging, it makes you feel not as much hate and anger and instead, offers a little more hope.”

Holman said the construction activity seemed to represent a healing process for a city that historically has taken more than its share of hits.

“You see the wounds being healed and it’s less dramatic, but when you look up and see that there’s no buildings there, it makes you remember those awful photos,” she said. “You can’t help but get choked up about it.”

A man in tattered clothes with a broad white beard sat with his back to the fence Thursday playing “Amazing Grace” on a flute over and over again. Meanwhile, a protester with John Kerry buttons on carried a sign warning Republican delegates visiting the city not to exploit the deaths of those who perished on Sept. 11, 2001.

The warning sign coupled with the protester’s buttons for the Democratic presidential nominee prompted Donnelly to surmise that the dissenter was really the one exploiting the tragedy for political purposes.

“It makes me kind of angry and he’s making this a difficult time for me to love free speech,” Donnelly said. “It’s heartless. But at least he has the right to voice that opinion and I do respect that.”