Sen. Lindsey Graham Lindsey Olin GrahamThe Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters Senate Democrats' campaign arm announces seven-figure investment to boost Graham challenger Graham: Comey to testify about FBI's Russia probe, Mueller declined invitation MORE (R-S.C.) says he still plans to "to get to the bottom" of President Trump's claims that Trump Tower was wiretapped by the Obama administration during the 2016 election.

"We owe it to [Trump]; we owe it to the American people to find out what happened in the 2016 election," Graham said in an interview with John Catsimatidis that aired Sunday on New York's AM 970.

"If there was a warrant issued to surveil the Trump campaign, I want to know about it. That would be disturbing because you'd have to have probable cause to get one. If there is no surveillance of the Trump campaign by the FBI or any other group, I think the American people need to know that," he added.

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"We will get to the bottom of whether or not the Trump campaign or anybody around the Trump campaign was surveilled by the Obama administration, or anybody else."

Graham also pledged to punish Russia for attempting to interfere in the 2016 election and blasted WikiLeaks for being "a Russian front."

"WikiLeaks is a Russian front … I want Russia to pay a price. As Republicans we should be very upset that a foreign power would try to interfere in our election," the lawmaker said.

"I want to punish the hell out of Russia for trying to interfere in our election," he added.

Graham also criticized the proposed border-adjustment tax, arguing that such a policy would end up harming the U.S.

"If you start putting a tax on products coming into the country, then you are going to drive up prices," he said.

"I want oil from Canada, but if you tax it from Canada, you're going to drive up the cost at the pump. So this border-adjusted tax is bad for retailers. I think it is going to drive up gas prices,” he added.

The lawmaker also praised Trump’s Supreme Court nominee Neil Gorsuch, calling him "one of the smartest people I've ever met."

"We are going to hopefully pass him out of the judiciary committee the week of March 20," Graham said.