Washington (CNN) Members of President Donald Trump's inner circle are frustrated that the Republican-led Senate Intelligence Committee subpoenaed Donald Trump Jr., multiple sources tell CNN.

Those close to Trump are exasperated that Republican Sen. Richard Burr, in their minds, just handed Democrats a talking point. Multiple Republicans had coalesced around Senate Majority Leader Mitch McConnell's talking point of "case closed" in recent days, but now Democrats can argue that even members of the President's own party don't agree that all Russia inquiries should end immediately.

Trump said Wednesday he was "very surprised" by the subpoena issued to his son, though it was issued more than two weeks ago, according to a source familiar with the matter.

"My son's a very good person, he works very hard," Trump said, adding that Trump Jr. offered his assistance during his 2016 campaign.

He repeated that his son is a "good person" and testified for "hours and hours," and was ultimately "exonerated by Mueller."

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