A second intelligence official who was alarmed by President Trump’s dealings with Ukraine is weighing whether to file his own formal whistle-blower complaint and testify to Congress, according to two people briefed on the matter.

The official has more direct information about the events than the first whistle-blower, whose complaint that Mr. Trump was using his power to get Ukraine to investigate his political rivals touched off an impeachment inquiry. The second official is among those interviewed by the intelligence community inspector general to corroborate the allegations of the original whistle-blower, one of the people said.

The inspector general, Michael Atkinson, briefed lawmakers privately on Friday about how he substantiated the whistle-blower’s account. It was not clear whether he told lawmakers that the second official was considering filing a complaint.

A new complaint, particularly from someone closer to the events, would potentially add further credibility to the account of the first whistle-blower, a C.I.A. officer who was detailed to the National Security Council at one point. He said that he relied on information from more than a half-dozen American officials to compile his allegations about Mr. Trump’s campaign to solicit foreign election interference that could benefit him politically.

Because the second official has met with Mr. Atkinson’s office, it was unclear whether he needs to file a complaint to gain the legal protections offered to intelligence community whistle-blowers. Witnesses who speak with inspectors general are protected by federal law that outlaws reprisals against officials who cooperate with an inspector general.

Still, testimony from someone with more direct knowledge of Mr. Trump’s efforts to use American foreign policy for potential political gain would most likely undermine conservatives’ attacks on the C.I.A. officer’s credibility.