(AP) - President Barack Obama visited the World Trade Center site Thursday, getting a firsthand look at the skyscraper being built to replace the twin towers destroyed in the Sept. 11, 2001, terror attacks.

"This is what the American spirit is all about," Obama said.

The president toured the 22nd floor of One World Trade Center in lower Manhattan, walking along the unfinished cement floor and stopping at easels set up with renderings of what the completed tower will look like.

Joined by first lady Michelle Obama, the president later came down to the base of the building and signed a large white beam - affixed with the words "One World Trade Center" painted in blue - that will be used in the construction. Obama inscribed on the beam, "We remember we rebuild we come back stronger!" followed by his signature.

For Obama, the visit offered an increasingly rare election year break from fundraising and other campaign-related events. But it also provided a president running for re-election with a potent picture of American resilience.

Obama told about 50 workers gathered near the beam that the building was an "incredible structure," and that it represented the American spirit. He was joined by a bipartisan cast of local officials, including Gov. Andrew Cuomo, Mayor Michael Bloomberg and New Jersey Gov. Chris Christie, a top surrogate for Republican presidential candidate Mitt Romney.

The skyscraper is expected to be completed in early 2014. As of Wednesday, steel had been erected up to the 104th floor, and workers had begun installing marble finishing on the ground floor.

Obama last visited the World Trade Center site in September for the 10th anniversary of the attacks.