A short list of office owners and developers in the District continues to vie for a lease from Arnold & Porter, the law firm currently located on 12th Street NW, but in the meantime another heavy hitter law firm is scouting the market.

Covington & Burling has eight offices internationally, including prime space in Washington at 1201 and 1275 Pennsylvania Ave. NW. Founded in 1919, Covington is frequently ranked as one of the most prestigious law firms in the city. It is the largest firm in the District, with more than 500 lawyers here. Eric Holder was a litigation partner in Covington’s Washington office before being nominated as attorney general by President Obama.

Several developers and landlords are aggressively pursuing the firm in hopes of delivering the 450,000 square feet it is seeking, a courtship that has grown more urgent as the federal government looks to cut back on its real estate needs.

Covington, like Arnold & Porter, is large enough and interested enough in securing high-end space that a lease from the firm could anchor a major new office development. Sources familiar with Arnold’s plans, who spoke on the condition of anonymity because they were not authorized by the firm to discuss the search, said the firm has considered remaining at 555 12th St. NW or moving to sites such as CityCenter D.C., currently under construction by Hines and Archstone, or a new office building that Boston Properties plans to build to replace the National Public Radio headquarters at 635 Massachusetts Ave. NW. An Arnold & Porter spokeswoman declined to discuss the particulars.

There are other options in the area as well. Gould Property Co. is marketing two development sites in the East End where it plans high-end office buildings and has been seeking tenants. One, at 900 New York Ave. NW, will be 620,000 square feet. The other, at 600 Massachusetts Ave. NW, will be 400,000 square feet. Douglas Development landed a $57 million deal last fall for a nearly 300,000-square-foot new headquarters for the Association of American Medical Colleges on the 600 block of New York Avenue NW and has more property in the area.

Covington’s current lease expires in 2016, the same year as leases end at the firms Latham & Watkins and Sidley Austin. Covington spokeswoman Rebecca Carr said the firm has so far decided not to extend its current lease as it considers its options.

“We’ve been happy with the location of our current offices at 1201 and 1275 Pennsylvania Avenue, and we’ve occupied the two-building complex here for nearly 30 years,” Carr wrote in an e-mail. “But in that time, the neighborhood around us has evolved in dynamic ways, and there are some interesting new developments and upcoming opportunities in the property market in the Penn Quarter and East End.”

Carr added that the firm could still decide to remain in the Pennsylvania Avenue offices.