FILE PHOTO - U.S. Representative Joaquin Castro (D-TX) speaks during the final night of the Democratic National Convention in Philadelphia, Pennsylvania, U.S. July 28, 2016. REUTERS/Mike Segar

(Reuters) - Representative Joaquin Castro has decided against running for the U.S. Senate in 2018, a campaign that would have pitted him against Republican Senator Ted Cruz, The New York Times reported on Monday.

Castro, 42, made his decision after several months of speculation about a potential primary clash with Congressman Beto O’Rourke, who has already announced his candidacy, the Times reported.

Both Castro and O’Rourke are part of the U.S. congressional delegation from Texas.

Castro and his brother, Julian, are both considered rising stars in the Democratic party. Julian Castro served as secretary of Housing and Urban Development under President Barack Obama.