CNN senior data reporter Harry Enten said on Wednesday that Vice President Kamala Harris joining the presidential race could dramatically weaken independent candidate Robert F. Kennedy Jr.’s campaign. Kennedy was polling above 12% against former President Donald Trump and President Joe Biden before Harris became the Democratic presumptive nominee, according to the RealClearPolling average. Enten, on “CNN Newsroom,” said Kennedy likely will not garner anywhere near this level of support now that Harris is in the running because his key constituency is dwindling as a result. Read: Florida Rep. M…