Republican Sen. Lindsey Graham — frustrated by the lack of answers from the FBI and White House — vowed Wednesday that Congress would "flex its muscle" to determine whether a warrant was ever ordered by the Obama administration to wiretap the Trump campaign.

FBI Director James Comey was asked by Graham and Judiciary Committee colleague Sen. Sheldon Whitehouse to confirm by Wednesday whether an active probe exists into alleged ties between the Trump campaign and Moscow.

More from NBC News:

Comey talks Russian meddling, Trump Tower with lawmakers

Trump supporters say leaked tax document vindicates the president

GOP skeptics harden opposition to health plan after CBO report

A bipartisan hearing is also being held Wednesday by the Senate Judiciary Committee's crime-and-terrorism subcommittee to start an inquiry into whether Russia meddled in last November's election.

"I think the country wants to know if there's something there there," Graham told TODAY.

The South Carolina senator said it's imperative he knows about any potential criminal investigation by the FBI because he wants Congress to move forward with its own investigation.

Meanwhile, Graham also wants Comey and Justice Department officials to confirm whether a warrant was ever issued by the feds to wiretap Donald Trump's Trump Tower residence in New York prior to the election.

Trump alleged in an explosive tweet on March 4 that the Obama administration had ordered such a move. He offered no evidence, and instead challenged Congress to get to the bottom of his claim.

Kevin Lewis, a spokesman for former President Barack Obama, has said he "nor any White House official ever ordered surveillance on any U.S. citizen. Any suggestion otherwise is simply false."

Graham said subpoenas would be issued and the nomination of the deputy attorney general would be held up if his request for information continues to be met with silence.

"I really don't know. If it's not true, just tell me it's not true. Why is it taking so long to get an answer?" Graham asked about getting a response from Comey.

When asked whether he believes a warrant was ever ordered, he added: "I'm suspicious of it."