WASHINGTON — Special Counsel Robert S. Mueller III on Monday revealed charges against three former Trump campaign officials – including onetime campaign chairman Paul Manafort – marking the first criminal allegations to come from probes into possible Russian influence in U.S. political affairs.

The charges are striking for their breadth, touching all levels of the Trump campaign and exploring the possible personal, financial wrongdoing of those involved, as well as what appeared to be a concerted effort by one campaign official to arrange a meeting with Russian officials.

One of the three charged, former Trump foreign policy adviser George Papadopoulos, admitted to making a false statement to FBI investigators who asked about his contacts with a foreigner claiming to have high-level Russian connections.

Manafort and longtime business partner Rick Gates, meanwhile, were charged in a 12-count indictment with conspiracy to launder money, making false statements and other charges in connection with their work advising a Russia-friendly political party in Ukraine.

Paul Manafort, then-Republican presidential candidate Donald Trump’s campaign manager, talks to the media from the Trump family box on the floor of the Republican National Convention in Cleveland on July 18, 2016. Reuters/Jonathan Ernst

The investigation, which the FBI began last year but escalated significantly with Mueller’s appointment in May, has taken a heavy toll on the Trump administration, repeatedly putting the president on the defensive as reports have emerged about the work the special counsel team is doing. With Monday’s revelations, a week that otherwise might have been spent with Washington focused on the Republican tax plan will have talking heads dissecting the criminal counts against former Trump campaign officials – and speculating about the next shoe to drop.

Papadopoulos’s plea agreement, signed earlier this month and unsealed Monday, described extensive efforts he made to try to broker connections with Russian officials and arrange a meeting between them and the Trump campaign. Emails show his offers were sometimes looked at warily, though more senior campaign officials at least entertained them.

Manafort and Gates pleaded not guilty in a brief appearance in D.C. federal court Monday afternoon. A federal magistrate judge put the men on home confinement and set a $10 million unsecured bond for Manafort, and a $5 million unsecured bond for Gates.

That means the men would be in debt to the government if they failed to show up for court, though they do not have to put any money down. Both surrendered their passports to the FBI. The next hearing in the case was scheduled for Nov. 2 before U.S. District Judge Amy Berman Jackson, a 2011 President Barack Obama appointee who previously worked as federal prosecutor in the District.

For their part, Trump, his spokeswoman and his lawyer sought to cast the charges as having nothing to do with the president.

White House Press Secretary Sarah Huckabee Sanders asserted Papadopoulos had an “extremely limited,” volunteer role in the campaign, and said that “no activity was ever done in an official capacity on behalf of the campaign in that regard.”

Rick Gates, then-campaign aide to Republican presidential candidate Donald Trump, attends the Republican National Convention in Cleveland on July 21, 2016. Associated Press/Evan Vucci

Ty Cobb, a White House lawyer overseeing the administration’s handling of the Mueller probe, said, “The one thing that’s clear is there’s no reference to collusion, no reference to the president.”

The president himself took to Twitter to declare: “Sorry, but this is years ago, before Paul Manafort was part of the Trump campaign. But why aren’t Crooked Hillary & the Dems the focus?????”

” . . . Also, there is NO COLLUSION!” he said in a follow-up tweet.

Sanders said Trump had “no intention or plan to make any changes with regard to the special counsel,” and Cobb said there had been no talk of possible pardons for Manafort or Gates.

“No, no, no. That’s never come up and won’t come up,” Cobb said in an interview.

Outside the D.C. courthouse, Kevin Downing, a lawyer for Manafort, said: “President Donald Trump was correct. There is no evidence that Mr. Manafort and the Trump campaign colluded with the Russian government.” Glenn Selig, a Gates spokesman, said, Gates “welcomes the opportunity to confront these charges in court.”

“This fight is just beginning,” Selig said.

Then-National Security Adviser Michael Flynn sits in the East Room of the White House on Feb. 10, 2017. President Obama warned Donald Trump against hiring Michael Flynn as national security adviser during an Oval Office meeting in the days after the 2016 election, according to three former Obama administration officials. Associated Press/Carolyn Kaster

The charges are a major step in the investigation, but they do not represent a conclusion. Court documents revealed that Papadopoulos, for example, has been cooperating with investigators for three months – having been first arrested and charged in July after landing at Dulles International Airport on a flight from Germany.

The information he provides could be key to furthering Mueller’s investigation into others, legal analysts said.

Papadopoulos admitted that he lied to the FBI about his interactions with people he thought had connections with the Russian government – essentially understating the conversations and claiming falsely that they had occurred before he joined Trump’s campaign.

In a January 2017 interview with the FBI, Papadopoulos told agents that a London-based professor claimed to him he had “dirt” on Hillary Clinton, including “thousands of emails.” But Papadopoulos said initially he viewed the professor as a “nothing.”

In reality, according to his plea, Papadopoulos understood the professor had connections to Russian government officials, and he treated him seriously. An email quoted in court filings appears to match one described to The Washington Post in August in which Papadopoulos identified the professor with whom he met as Joseph Mifsud, the director of the London Academy of Diplomacy.

After a March 2016 meeting with the professor, who was not identified in court records, Papadopoulos emailed a campaign supervisor and other members of the campaign’s foreign policy team. He claimed the professor had introduced him to “Putin’s niece” and the Russian ambassador in London, and the purpose was “to arrange a meeting between us and the Russian leadership to discuss U.S.-Russia ties under President Trump,” court documents say.

The government noted the woman was not Russian President Vladimir Putin’s niece, and while Papadopoulos expected the professor would introduce him to the Russian ambassador, that never happened. But in the months that followed, Papadopoulos continued to correspond with the woman and the professor about a meeting between the Trump campaign, possibly including Trump himself, and Russian officials.

“The Russian government has an open invitation by Putin for Mr. Trump to meet him when he is ready,” Papadopoulos wrote to a senior policy adviser for the campaign on April 25.

At one point, a campaign official forwarded one of Papadopoulos’s emails to another campaign official, saying, “We need someone to communicate that DT is not doing these trips. It should be someone low level in the campaign so as not to send any signal.” DT would appear to be a reference to Donald Trump.

Papadopoulos’s effort continued into the summer of 2016, and in August 2016, a campaign supervisor told Papadopoulos and another foreign policy adviser they should take a trip to Russia. That ultimately did not take place, according to the plea.

Lawyers for Papadopoulos said in a statement: “We will have the opportunity to comment on George’s involvement when called upon by the Court at a later date. We look forward to telling all of the details of George’s story at that time.”

In a separate indictment, the special counsel alleged that Manafort and Gates laundered money for nearly a decade through scores of U.S. and foreign corporations and accounts, and gave false statements to the Justice Department and others when asked about their work on behalf of a foreign entity. The time period stretched into at least 2016, though it did not seem to involve the Trump campaign.

According to the indictment, Manafort and Gates arranged to hire two Washington-based lobbying firms to work on behalf of their Ukrainian clients, arranging meetings with U.S. officials and boosting their public image in the United States.

Though it was not named, one of the firms referenced in the indictment was The Podesta Group. Tony Podesta, the head of the firm, announced to colleagues Monday he was stepping down. The other firm is Mercury LLC, according to people familiar with the matter. A partner at Mercury said the firm “believed our work was intended to serve an important and proper purpose.”

Prosecutors say that Manafort and Gates arranged for a Brussels-based nonprofit to nominally hire the Washington companies to hide the fact that the two men were working for Ukrainian government officials; otherwise they would have been required to register under the Foreign Agents Registration Act.

In fact, prosecutors allege, Manafort was communicating directly with then-Ukrainian President Viktor Yanukovych about the effort, promising in 2012 to provide him weekly updates.

Prosecutors say that when the Department of Justice approached Manafort and Gates in 2016 and 2017 about whether they should have registered as foreign agents for the work, they responded with false and misleading letters, according to the indictment.

Manafort and Gates also were accused of trying to hide funds kept in foreign bank accounts – Manafort from 2011 to 2014 and Gates from 2012 to 2014. And Manafort was accused of filing fraudulent tax returns – stating on tax forms he filed from 2008 to 2014 that he controlled no foreign bank accounts.

All told, more than $75 million flowed through offshore accounts, the special counsel alleged.

From 2008 to 2014, according to the indictment, Manafort arranged to wire $12 million from offshore accounts to pay for personal expenses – including $5 million to a home renovation contractor in the Hamptons, more than $1.3 million to a home entertainment and lighting vendor based in Florida, $934,000 to an antique rug dealer in Alexandria, and $849,000 to a men’s clothier in New York.

Law enforcement’s interest in Manafort dates back to at least 2014, according to a person familiar with the case.

While Mueller’s probe has focused on Manafort and former national security adviser Michael Flynn, investigators have shown interest in a broad array of other topics.

Those include meetings the president’s son-in-law, Jared Kushner, had with the Russian ambassador and a banker from Moscow in December, and a June 2016 meeting at Trump tower involving the president’s son, Donald Jr., and a Russian lawyer. Mueller’s team has requested extensive records from the White House, covering areas including the president’s private discussions about firing James B. Comey as FBI director and his response to news that Flynn was under investigation, according to two people briefed on the requests.

Mueller is also investigating whether Trump obstructed justice leading up to Comey’s firing.