Story highlights Stuart Jolly, Donald Trump's national field director, tendered his resignation to Trump on Monday

Jolly was a longtime loyalist to Trump's campaign manager Corey Lewandowski

(CNN) Donald Trump's national field director resigned Monday amid a staff shakeup that put Scott Walker's former campaign manager in charge of the campaign's ground operation.

Stuart Jolly, the national field director, tendered his resignation to Trump, two days after Trump met with senior staff and officially elevated Trump's recently-hired national political director Rick Wiley above Jolly.

"I left. I wasn't pushed, I wasn't shoved, I wasn't asked to leave," Jolly told CNN Monday in a phone interview.

Jolly was a longtime loyalist to Trump's campaign manager Corey Lewandowski, and Jolly's departure shrinks the circle of loyal aides Lewandowski has around him as Paul Manafort, Trump's recent hire to manage the convention strategy, gains more clout in the Trump campaign.

"I don't want to hurt Mr. Trump and I certainly don't want to hurt Corey," Jolly told CNN, adding that it was simply time to leave amid the campaign shakeup.

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