Fellow Republican Vice President Mike Pence was called in as president of the Senate to break a tie vote on advancing Thomas Farr's nomination as a U.S. district judge in North Carolina, after Flake voted "no." 

Flake is a strong advocate for the protection bill, known as the Special Counsel Independence and Integrity Act, which would make it harder for President Donald Trump to undermine the investigation of Russian meddling in the 2016 presidential election. 

The measure has already been approved at the committee level with support from both parties. 

Trump has called Special Counsel Robert Mueller's probe, which is also looking into possible collusion between Moscow and Trump's 2016 presidential campaign, a witch hunt. Russia denies interfering in the 2016 election and Trump has denied any collusion occurred. 

Speaking to reporters earlier on Wednesday, Flake, who is retiring soon, said he believed the bill could pass but that he had been told "somebody will block it."