Top U.S. Senator threatens to subpoena FBI over Trump wiretapping claims

Top Republican Senator Lindsey Graham has warned that if FBI Director James Comey does not provide evidence over the validity of President Donald Trump's wiretapping allegations, then he will subpoena the information from the bureau if needed.

Earlier this month, Trump alleged that former president Barack Obama ordered his phones to be wiretapped at Trump Tower during the campaign.

Last week, Graham and Senator Sheldon Whitehouse asked the Justice Department last week to provide any evidence that would support Trump's claims.

"We wrote a letter -- Sen. Whitehouse and myself -- wanting to know if there's evidence of a warrant issued by the Trump campaign. He hasn't answered that letter or confirmed if there's a real investigation of the Trump campaign. He needs to answer the letter and give the nation some information about what's going on here," the South Carolina Republican told CNN.

If the FBI does not provide the information, Graham said he and other senators may subpoena it.

"I want to get to the bottom of it. The FBI would know if a warrant was issued. They would know if a warrant was applied for. I want to answer that question. If they do not provide the answer to that letter we wrote in a bipartisan fashion, there will be a bipartisan subpoena following the FBI," he said.

Graham, who is leading one of the three congressional investigations into Russia's interference in the US election, has clearly stated that the lack of an answer from the FBI is causing him to become suspicious.

"I've seen no evidence of collusion between the Trump campaign and Russia. I've seen no evidence of a wiretap being requested by the Department of Justice, a warrant. But the longer it takes to answer my letter, the more concerned and suspicious I'm beginning to be," he said.

The senator added that if the FBI does not respond to lawmakers' requests for information, some may be willing to block more appointments to the Trump administration.

"If there's not a criminal investigation of the Trump ties to Russia, I think the country needs to know it. Congress needs to know it, and he has never promised to answer that question. Chairman (Chuck) Grassley said something very important yesterday, that he would be willing to block the deputy attorney general's nomination until Director Comey gave us the information we sought regarding warrants and investigations," Graham said.

However, the White House is on the backfoot regarding Trump's claim earlier this month that Obama had his "wires tapped" toward the end of the campaign, as press secretary Sean Spicer said Monday the President wasn't referring to wiretapping when he tweeted about wiretapping.

"I think there's no question that the Obama administration, that there were actions about surveillance and other activities that occurred in the 2016 election.The President used the word 'wiretaps' in quotes to mean, broadly, surveillance and other activities," Spicer had said.

Meanwhile, top Republicans in Congress have expressed their dissatisfaction about getting answers from the FBI, as lawmakers trying to investigate Russia's meddling in the US election say they've continued to see no evidence of President Donald Trump's claim that he was wiretapped by his predecessor.