NEW YORK (CNN) -- Two portraits of George Washington by renowned artist Gilbert Stuart, one of them commissioned as a gift for Alexander Hamilton, are to be auctioned Wednesday at Sotheby's in Manhattan.The Hamilton painting depicts the first American president during his final year in office. Washington is seated in a black velvet suit jacket with a sword resting across his lap and holding a document he has signed.Sotheby's predicted it will sell for more than $10 million.Stuart (1755-1828), who portrayed most of the notables of the early United States, did nearly 100 paintings of Washington. His best-known image of the president, a head from an incomplete portrait, graces the $1 bill.The "Constable-Hamilton" portrait, as it is known, is the only one of Stuart's paintings of Washington with a seascape in the background.A wealthy merchant-trader named William Constable commissioned the portrait in 1797 for Hamilton, a fellow New Yorker who was the nation's first secretary of the treasury.Art historians believe it to be a tribute to Hamilton's actions to boost American trade by spearheading the creation of the U.S. Navy and Coast Guard and negotiating a treaty with Britain to halt seizures of American cargo ships, according to the auction catalog.The portrait is among a group of works being sold by the New York Public Library, which is unloading 15 paintings and four sculptures to raise money for its endowment to acquire books and manuscripts."The quality is clearly there. It is a magnificent portrait in a wonderful state of preservation, [it] has been obviously very carefully taken care of by the library for many years," said Peter Rathbone, Sotheby's director for American paintings and sculpture."The fact that it does come directly through Hamilton's family to the library, and Hamilton's importance as a figure in this country certainly adds to the luster and importance of the work," Rathbone said.The picture is considered more valuable than a second Stuart portrait of Washington also consigned by the library to Sotheby's.The second portrait shows Washington standing, his left hand holding a sword and his right hand resting on a copy of the Constitution unrolled on a table.This work, from 1796, is known as the "Munro-Lenox" portrait for its two 19th century owners. Peter Munro was a nephew of John Jay, the nation's first chief justice.Munro's family sold it to James Lenox, who founded a library that merged with other collections to form the New York Public Library.Rathbone said it is unusual for two high-quality Washington portraits by Stuart to be on the market at the same time."They do appear with some regularity, but never works as important or as rare," he said."They should ideally go to a public institution," Rathbone added, "so they remain on public view. We have no control over that."The National Portrait Gallery previously acquired a similar full-length Stuart portrait of a standing Washington for $20 million.