Until March, Donald Trump’s campaign to become the Republican presidential nominee seemed almost uniquely lacking in leaks and infighting. But now, in the words of one source, there is “a snake in the garden”.

The arrival of veteran operative Paul Manafort into Trump’s inner circle to lead his effort to clinch enough delegates to win the nomination has led to much of the campaign devolving into a turf war between the newcomer and longtime campaign manager Corey Lewandowski.
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Manafort, a veteran delegate wrangler with experience going back to the 1976 Republican National Convention, used the campaign’s problems managing the complex delegate selection process as his path into Trump’s inner circle.

He is also a longtime friend and business partner of Trump’s confidant Roger Stone, who left the campaign in August after repeated conflict with Lewandowski. It has been suggested that Manafort’s emergence is the latest round in the ongoing battle between Stone and Lewandowski for Trump’s ear. While the Trump campaign in early March hired a number of veteran operatives who had previously worked for Republican rival Ben Carson to help prepare for a contested convention, the delegate hunt had not been prioritized to the extent that other campaigns, like that of Ted Cruz, had done.

http://www.theguardian.com/us-news/2016/apr/19/donald-trump-campaign-rift-delegate-panic-paul-manafort