The Senate intelligence committee has asked 20 people to be questioned in its investigation of Russian interference in the 2016 presidential election, the panel’s chairman said Wednesday.

“This one is one of the biggest investigations the Hill has seen in my time here,” Chairman Richard Burr, a North Carolina Republican, said at a news conference with committee vice-chairman Mark Warner.

Burr’s been in the Senate since 2005 and served in the House since 1995.

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