By Eli Watkins

CNN

WASHINGTON (CNN) -- Virginia Sen. Mark Warner pledged on Tuesday that he would press President Donald Trump's former campaign chairman Paul Manafort for answers.

The Democratic senator and ranking member on the Senate intelligence committee said on CNN's Erin Burnett "OutFront" that allegations about Manafort's dealings in Ukraine and other open questions meant that the committee would speak with him as part of its probe into alleged Russian interference in the presidential campaigns and collusion between the Trump campaign and Russia.

"We have to talk to Mr. Manafort," Warner said. "We're going to need to bring him in."

Manafort, in a statement on Monday, denied any connection between himself and the hack of the Democratic National Committee, which the US intelligence community has accused Russia of perpetrating.

Warner said Manafort would be one of several of Trump's associates the panel would interview, adding that some investigatory work had already begun.

"We're already starting to interview individuals," Warner said.

Trump brought on Manafort last spring to manage his delegate operation going into a potentially contested Republican National Convention. Following the ouster of Corey Lewandowski, Manafort led the campaign for months. Trump eventually brought on Steve Bannon and Kellyanne Conway to lead his campaign as Manafort exited, amid some questions about his relationship with Russia.

Manafort had done significant lobbying work overseas and worked for former Ukrainian President Victor Yanukovych, the pro-Russian leader who left the country in early 2014.

His role in the Trump campaign has drawn renewed scrutiny recently, especially after FBI Director James Comey confirmed on Monday that the government was looking into potential collusion between the Trump campaign and Russia.

Both the Senate and House intelligence committees are running investigations into Russia's activities, and Warner has regularly stressed the regard he holds for this work.

"This is probably the most important thing I've ever taken on in my public life," Warner said.