Maine Medical Center eyes leasing the entire One Riverfront Plaza building for administrative offices.

The largest and most prominent office building in downtown Westbrook, vacant since November, could soon be filled.

Susan Pertier, the communications manager for Maine Medical Center, confirmed this week that the MaineHealth hospital is considering leasing the entire One Riverfront Plaza building for administrative offices.

The six-story, 134,000-square-foot building at the foot of Saccarappa Falls is seen as a lynchpin to downtown Westbrook’s vitality.

The move would mark a huge boost for the city, as the departure late last year of insurance company Disability RMS was considered a substantial blow, with more than 350 employees relocating to South Portland. Disability RMS employees had routinely utilized the downtown riverwalk and neighboring restaurants and other businesses.

“Maine Medical Center is exploring various options related to administrative functions that can be delivered most efficiently offsite from our main campus on the Portland peninsula,” Pertier said in an email Monday, adding that the company has been “exploring” the use of Riverfront Plaza.

For the city, the lease could represent an even larger influx of employees than Disability RMS, which did not use all six floors.

City officials would not confirm the status of a deal between Maine Medical Center and the building’s owners this week, but rumors about it have been circulating throughout the city for several weeks. Assistant City Administrator Bill Baker said the city has “delivered on its promise” to work closely with the owners of the building ever since news of the Disability RMS departure came.

“We remain hopeful that the fruits of our labor will be a critical downtown building filled with a dynamic work force that will drive economic development in the downtown, enhance opportunity for every land owner and business person in the downtown district and continue this string of superb news for the Westbrook commercial market,” Baker said in an email Tuesday.

Dan Greenstein, the listing broker for One Riverfront Plaza for the Boulos Co., declined to comment this week, stating that, by company policy, “we don’t disclose the status of any negotiations with regard to properties or clients we represent.”

According to the listing, Riverfront Plaza features a fitness room, locker rooms, cafeteria and a dining area. The parking garage attached to the building has 540 parking spaces. The property is listed at a rate of $16.50 per square foot a year.

The building is owned by Roebling Investment Co., which is based in Hackensack, N.J. Donald Hanson, the spokesman for the company, declined to comment Wednesday.

One Riverfront Plaza, across from the Dana Warp Mill, was built for $17 million and opened in 2004. One year later, original developer Tim Flannery sold the building to Roebling. Hanson told the American Journal at the time that the fact that the building had a stable, long-term tenant was a major factor behind the decision to purchase it.

Westbrook Mayor Colleen Hilton said Tuesday that Baker has been working with the building’s owners to secure a new tenant since the Disability RMS announcement last year.

“A building of that size is no easy replacement in today’s economy, but through hard work and diligence it looks like Westbrook will be seeing a new tenant of considerable size in the building in the near future,” she said.

Due to the potential difficulty in securing a single tenant for the large building, Baker said last year that he had been working to find multiple tenants to possibly lease smaller spaces.

Hilton hinted that a more prominent deal was in the works during her address at the Westbrook inaugural ceremony in December.

She said this week that it would be “premature” to announce particulars, but said the interest is real.

“The excitement is palpable and we are very pleased that the efforts to focus on our riverfront, recreational amenities and business community in Westbrook is truly looking up,” she said.

Riverfront Plaza is at the center of big changes in the downtown. The newly opened Bridge Street Bridge will be complemented by an accompanying pedestrian bridge and other upgrades by this summer. On the river, Sappi Fine Paper and local organizations are continuing to work to remove the hydroelectric dams at Saccarappa Falls, and establish natural fish passage to support wildlife and promote recreation.

Meanwhile, city officials say they have been pleased with the recent business activity downtown. Hilton mentioned the recent investment by James Para in 1 Westbrook Common, the brewery and potential urgent-care facility on the former Maine Rubber property, and the Ash Street office building developed by Rob Mitchell.

“Good things are happening and we are grateful to all of the people investing in Westbrook’s future,” she said.

One Riverfront Plaza, the former home of Disability RMS, could soon be filled by Maine Medical Center administrative offices.