WASHINGTON (Reuters) -Republican President Donald Trump said on Sunday he was not joking about seeking a third presidential term, which is barred by the U.S. Constitution, but that it was too early to think about doing so. Trump, who took office on January 20 for his second, non-consecutive White House term, has made allusions to seeking a third one but addressed it directly in a telephone interview with NBC News. U.S. presidents are limited to two four-year terms, consecutive or not, according to the 22nd Amendment of the U.S. Constitution.