After Gabbard faced a public questioning, one of senators three still on the fence—Susan Collins—now says she's a 'yes' vote.

A source with knowledge of the proceedings told ABC News that newly confirmed CIA Director John Ratcliffe, former NSA adviser Robert O'Brien and former Sen. Richard Burr, a former Senate Intelligence Committee chairman, have been making calls to senators on Gabbard's behalf. Gabbard has also talked to senators since her hearing, a source said.

Collins, a pivotal swing vote on the Senate Intelligence Committee, is expected to play a key role in advancing Gabbard’s nomination as the committee meets on Tuesday.