June 24 (Reuters) - Federal Reserve Bank of Dallas President Robert Kaplan said on Thursday he sees “upside risk” to his forecast for 3.4% inflation this year and 2.4% inflation next year, as supply-demand imbalances may persist longer than anticipated. Whereas initially it was a narrow number of items where prices were rising, it is “broadening out,” Kaplan said in a virtual appearance at the Austin Headliners Club, adding that to manage the range of inflation risks ahead, the Fed ought to “sooner rather than later” reduce its support for the economy by trimming its $120 billion a month in asset purchases. (Reporting by Ann Saphir Editing by Chris Reese) Our Standards: The Thomson Reuters Trust Principles.