ROUGH CUT (NO REPORTER NARRATION) A lone Republican lawmaker on Wednesday vowed to block judicial nominations in the U.S. Senate until Republican leader Mitch McConnell agrees to hold a vote on a measure to protect a probe into Russia's role in the 2016 presidential election.

Senator Jeff Flake made the threat after McConnell blocked Flake's measure from moving forward.

The Special Counsel Independence and Integrity Act would make it harder for President Donald Trump to undermine the investigation into Russian meddling and any coordination between Moscow and the Trump campaign.

Moscow denies interfering and Trump has repeatedly dismissed Special Counsel Robert Mueller's investigation as a political witch hunt.

"I will not vote to advance any of the 21 judicial nominees pending in the Judiciary Committee, or vote to confirm the 32 judges awaiting confirmation on the Senate floor until (the bill) is brought to the full Senate," Flake said in a floor speech after his effort to win consent for a vote failed.

Flake, who is retiring from the Senate, used the same strategy earlier this year to obtain a Senate vote on an amendment to rein in Trump's power to impose tariffs on foreign goods.

His vote is especially crucial on the 21-member Senate Judiciary Committee, which Republicans control by only a single seat.

But Flake could also make life difficult for McConnell on actions in the 100-seat Senate, which Republicans control by only a 51-49 seat margin through the end of the year.