It's been cited many, many times. The only problem is, it's all wrong.
The wildest expression of the theory came, as it often does, from MSNBC's Rachel Maddow, who told viewers on March 8 that "something weird" happened to the GOP platform on "that Ukraine and Russia thing" when the Trump team "jumped right up on that and they insisted that that plank only, that one, had to be taken out, that language could not stand."
Maddow's charge echoed what Democrats have long been saying about the issue. "Donald Trump changed the Republican platform to become what some experts would regard as pro-Russian," Clinton campaign manager Robby Mook told ABC on July 24 of last year. Some journalists, including those less fevered than Maddow, joined in to report the so-called weakening as an accepted fact. National Public Radio, for example, explained "how the Trump campaign weakened the Republican platform on aid to Ukraine."
Much of the reporting and commentary appears to spring from a single story, published in the Washington Post on July 18, 2016, with the headline "Trump campaign guts GOP's anti-Russia stance on Ukraine.Read more at WashingtonExaminer