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 possible personal financial wrongdoing by 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 foreigners 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.

[Ukrainians cheered by news of Manafort's indictment]

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's 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 his extensive efforts to try to broker connections with Russian officials and arrange a meeting between them and the Trump campaign. Emails show that 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.

[Here is who is under investigation — and why]

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 a 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 that 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."

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 that 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 that Gates "welcomes the opportunity to confront these charges in court."

"This fight is just beginning," Selig said.

[Mueller's moves send message to other potential targets: Beware, I'm coming]

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 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 had 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