NEW YORK — Joseph P. Kennedy III, a 31-year-old Massachusetts prosecutor, will run for Congress this year in a bid to resurrect the dynasty of America's most famous political family, reports said Thursday.

Kennedy is in the final stages of preparing a Congressional run, with hopes to succeed retiring Democratic Representative Barney Frank, the Boston Globe and Rhode Island Public Radio reported, quoting family and Democratic sources.

Should Kennedy win a seat in the House of Representatives, his family would return to national politics for the first time since Patrick Kennedy -- son of the clan's late patriarch Edward Kennedy -- left office early last year.

The congressional hopeful, son of former representative Joseph P. Kennedy II and grandson of the assassinated Robert F. Kennedy, is an assistant district attorney in Middlesex county.

He speaks Spanish fluently, and graduated from Stanford University and Harvard Law School, according to his biography on the website of the prosecutor's office.

The media reports said he is opening an exploratory committee, a legal step that would allow him to start raising campaign funds, as well as preparing to quit his job at the district attorney's office.

One or more members of the storied and troubled US political clan have served in Washington since John F. Kennedy successfully ran for a House seat from Massachusetts in 1946, before going on to win the presidency.

The death in 2009 of senator Edward Kennedy was seen as a landmark, leaving no Kennedys in high political office and ending the last high-profile public link to the era of the assassinated JFK.

The Kennedys were once an unbeatable political brand in liberal Massachusetts, but their decline came into relief when a special election to fill Edward Kennedy's vacated Senate seat was won by Republican Scott Brown.