Story highlights Donald Trump's list of potential vice presidential nominees is "very small," a top aide says

Trump's two top aides on Sunday downplayed a reported rift between them

Washington (CNN) Donald Trump has narrowed his potential running mates to a "very small" list, his top aide said Sunday.

In an appearance on "Fox News Sunday," Trump campaign manager Corey Lewandowski -- who is leading the vice-presidential search process -- said the vetting team has "started to shrink down that pool."

"I can say that the list is very small and we have a very good understanding of who those handful of individuals will be and ultimately the decision will be made by Mr. Trump," Lewandowski said.

He said the final decision will be up to Trump, the presumptive Republican nominee, but aides are now identifying the strengths and weaknesses of each option.

"What we are doing right now is making sure that we've done our due diligence so that when he chooses the person he wants, we can give him the pros and cons of each of those individuals.... so we feel very good where we are in the process," Lewandowski said.

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