NEW YORK (Reuters) - New York state Senator Adriano Espaillat conceded defeat on Monday in his primary election bid to oust long-serving Democratic U.S. Representative Charles Rangel and dropped a lawsuit challenging the results.

Espaillat initially conceded defeat two weeks ago on the night of the primary, when a preliminary count suggested that Rangel, a 21-term congressman, had easily turned away his strongest challenge yet.

Espaillat, a Dominican-American with strong Latino support, later questioned the results, saying his campaign had received numerous reports of voters being turned away at the polls.

"I am here to acknowledge that we came short - 2 percent," Espaillat told a news conference broadcast by the NY1 cable station.

He also said he would drop a lawsuit he filed last week challenging the results.

The race was a trial of strength for Rangel, a once-towering figure in New York politics diminished by an ethics scandal.

The House censured him in 2010 for ethics violations, including failing to pay some income taxes. He stepped down that year as chairman of the powerful tax-writing House Ways and Means Committee.

New boundaries have transformed his traditionally African-American district into one that is now heavily Hispanic.

The winner of the primary will be virtually assured of winning the November general election to represent the district, a Democratic stronghold.

(Reporting by Edith Honan; Editing by David Brunnstrom)