WASHINGTON — It was a mystery that gripped Washington for the better part of two weeks, filled with clandestine meetings at the White House, classified intelligence documents and confidential sources. And a central question was unanswered: Who showed the chairman of the House Intelligence Committee reports indicating that President Trump or members of his transition team may have been “incidentally” caught up in foreign surveillance by American spy agencies?

The New York Times reported Thursday that a pair of White House officials had helped provide the intelligence to the committee’s chairman, Representative Devin Nunes, Republican of California. The revelation has fueled criticism that Mr. Nunes, who had been a member of Mr. Trump’s transition team, has been too eager to do the bidding of the Trump administration while his committee is supposed to be conducting an independent investigation of Russia’s meddling in the presidential election.

That investigation has now descended into a partisan sideshow, and the White House on Friday returned to the unproven claim that started it all: Mr. Trump’s accusation that he was “wiretapped” by President Barack Obama.

Keeping up with the twists and turns in the unfolding story has been no easy feat. Here is a timeline that lays out how this bizarre Washington drama has unfolded.

In a series of early-morning Twitter messages, Mr. Trump accused Mr. Obama of wiretapping Trump Tower before the presidential election.

He then posted a final message about the poor ratings of his successor on “Celebrity Apprentice,” Arnold Schwarzenegger, and headed out to play golf.

Mr. Nunes rejected Mr. Trump’s allegation, saying that, if taken literally, the president is “wrong.”

Sean Spicer, the White House press secretary, told reporters “there’s more to come” as far as evidence to support Mr. Trump’s claim of wiretapping.

That evening, Mr. Trump was asked about his wiretapping accusations during an interview with Fox News, and responded by saying he had been “seeing a lot of things.”

“I think you’re going to find some very interesting items coming to the forefront over the next two weeks,” Mr. Trump said.

At the first public hearing in the House investigation, James B. Comey, the director of the F.B.I., took the extraordinary step of announcing that the agency is investigating possible collusion between members of Mr. Trump’s campaign and Russian officials.

Mr. Comey also dismissed Mr. Trump’s claim that he was wiretapped.

Sometime that day — the precise timing remains unclear — Mr. Nunes received a call from a person he has described only as a source. The call came as he was riding across town with a staff member in an Uber vehicle. Mr. Nunes quickly got out of the car and went to the White House. There, he has said he reviewed “dozens” of intelligence reports.

At a hastily arranged news conference, Mr. Nunes revealed he had received information about the incidental intelligence collection by American spy agencies, saying he could discern the identities of Trump associates from reading reports about intercepted communications, which were shared among Obama administration officials with top security clearances. He refused to identify sources, suggesting they were whistle-blowers trying to expose wrongdoing at great risk to themselves.

Mr. Nunes then dashed off to the White House to brief Mr. Trump on what he had learned the day before and followed up that meeting with an impromptu news conference in the driveway of the White House. There, he stressed that while the new information did not validate Mr. Trump’s wiretapping claim, it did show that the president might have been correct to say he had been surveilled.

Around the same time, Mr. Trump was asked by reporters if he felt vindicated. “I somewhat do,” he said. “I must tell you I somewhat do.”

Around 5 p.m., Representative Adam B. Schiff of California, the top Democrat on the Intelligence Committee, held his own news conference denouncing Mr. Nunes for briefing Mr. Trump before talking to members of his own committee.

Mr. Nunes apologized behind closed doors to committee members for not sharing the information before going to Mr. Trump and the news media.

But later that day, Mr. Nunes appeared on Fox News to defend his decision to go to Mr. Trump. “I felt I had a duty and obligation to tell him because as you know he’s been taking a lot of heat in the news media,” he said.

Mr. Nunes told reporters he was canceling plans for an open hearing with James R. Clapper Jr., the former director of national intelligence; John O. Brennan, the former C.I.A. director; and Sally Q. Yates, the former acting attorney general. Instead, Mr. Nunes said the committee would hold a closed session with Mr. Comey and Adm. Michael S. Rogers, the director of the National Security Agency. He also refused to answer questions about whether his disclosures about incidental intelligence were based on information that had come from the White House.

In a Twitter message less than an hour later, Mr. Schiff called Mr. Nunes’s decision to cancel the committee’s next public hearing “an attempt to choke off” public access to information, accusing him of caving to pressure from White House officials.

Later that day, Mr. Nunes told The Times that he had bypassed Mr. Schiff and gone straight to the White House with the information because of the Democrats’ “relentless” political attacks and his “duty” to tell Mr. Trump. “What I was trying to do was get to the president as quick as possible,” he said.

After CNN reported that Mr. Nunes was spotted at the White House on March 21, Jack Langer, the congressman’s spokesman, acknowledged that his boss had met his source on the White House grounds. Mr. Langer said Mr. Nunes needed access to a secure location where people with security clearances could legally view classified information, though such facilities can also be found in the Capitol building and at other locations across Washington.

Mr. Langer added in a statement that Mr. Nunes “began looking into this issue even before President Trump tweeted his assertion that the Trump Tower had been wiretapped.”

The closed-door hearing with Mr. Comey and Admiral Rogers was quietly scrapped, prompting Democrats to accuse Mr. Nunes of being more eager to do the bidding of the Trump administration than to run an independent investigation.

But Mr. Nunes said he would stay on despite Democrats’ calls that he step aside. “Why would I not?” he told reporters.

The Times reported the identities of two White House officials who helped provide Mr. Nunes with the intelligence about incidental surveillance.

According to several current American officials, Ezra Cohen-Watnick, the senior director for intelligence at the National Security Council, found the intelligence. Michael Ellis, a lawyer who works on national security issues at the White House Counsel’s Office and was previously counsel to Mr. Nunes’s committee, then allowed the congressman to view it.

One official said the intelligence had been found as part of an effort to come up with evidence to back Mr. Trump’s wiretapping claims, which would be using intelligence to advance the political goals of the Trump administration.

Mr. Langer, Mr. Nunes’s spokesman, refused to confirm or deny the report.

Sean Spicer, the White House press secretary, reasserted Mr. Trump’s surveillance allegations, saying that members of Mr. Obama’s administration had done “very, very bad things.”

“The question is why? Who else did it? Was it ordered? By whom?” Mr. Spicer said. “But I think more and more the substance that continues to come out on the record by individuals continues to point to exactly what the president was talking about that day, on March 5.”

Mr. Trump’s Twitter messages were on March 4.