Arizona Sen. John McCain. Twitter/CNN John McCain suggested on Tuesday that he expects more bombshell revelations to emerge in President Trump's Russia scandal.

The Republican senator's comments came after Donald Trump Jr., under increased scrutiny because of his June 2016 meeting with a Russian government lawyer, released an email chain detailing how the meeting was arranged.

"Another shoe just dropped," McCain told a CNN reporter outside a Senate office in Washington. "There'll be many more shoes that drop."

The emails, which Trump Jr. posted on Twitter Tuesday morning after learning The New York Times was preparing to publish them, reveal how a British music publicist with ties to President Trump offered to arrange a meeting between Trump Jr. and the Russian attorney, Natalia Veselnitskaya.

Trump Jr. is promised incriminating information about Hillary Clinton, and the publicist makes clear the information is "part of Russia and its government’s support for Mr. Trump."

President Trump's son-in-law Jared Kushner and then-campaign manager Paul Manafort also attended the meeting at Trump Tower. Trump Jr. insists that no dirt on Clinton was ever delivered.

For McCain, it's not the first time he's telegraphed his concern with Trump's deepening Russia scandal. In May, after Trump cited the Russia investigation as his rationale for firing FBI Director James Comey, McCain compared the scandal to Watergate.

"We've seen this movie before. It's reaching Watergate size and scale," McCain said. "This is not good for the country."

"It's the centipede that the shoe continues to drop, "he added, using similar language to his comments on Tuesday. "Every couple of days, there's a new aspect of this really unhappy situation."

McCain also used similar language in April when he told ABC that "every time we turn around, another shoe drops from this centipede."

McCain's comments on Tuesday make him one of just two Senate Republicans to comment on the Trump Jr. email chain. South Carolina Sen. Lindsey Graham said he found the conversation "disturbing."

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