Less than a month after declaring his long-shot candidacy for president in 2015, Donald Trump told a Las Vegas gathering he would get along “very nicely” with Russian President Vladimir Putin and there was no need to continue U.S. sanctions against Russia.

“I know Putin, and I’ll tell you what: We get along with Putin,” Trump said at the FreedomFest libertarian conference.

The encounter meant little in the early days of a campaign that many regarded as another Trump exercise in personal vanity. But three years later, the episode involving young Russian gun-rights activist Maria Butina marks one of the earliest known and most direct efforts in the Russian government’s campaign to probe the U.S. political system and Trump's unlikely ascendancy within it.

Earlier this month, Butina pleaded guilty to serving as an unregistered agent of the Kremlin. Although her case was not brought by Russia special counsel Robert Mueller, the disclosures in Butina's case were among several recent developments that have brought a series of federal investigations closer into focus.

The fast-moving events in the final weeks of 2018 also included documents outlining a wide range of criminal conduct implicating some of the president's former closest aides.

Together, these cases have offered vivid accounts of the forces that now threaten Trump's presidency.

The end-of-year developments included the Dec. 12 sentencing of Trump's former personal attorney and fixer, Michael Cohen, to three years in prison for making hush-money payments to two women who claimed affairs with Trump, and for lying to Congress about Trump's efforts to secure a Moscow real-estate deal.

On the same day, the company that owns the National Enquirer, headed by Trump associate David Pecker, agreed to cooperate with investigators to avoid prosecution for its role in the payoffs to women to block sex scandals from spilling into the 2016 presidential campaign.

More:Trump's tweets: Judges in government secrecy cases say they are 'speculation' and not 'pure fact'

More:Putin's holiday message to Trump: Russia 'open to dialogue ... on most extensive agenda'

And on Dec. 18, a federal judge in the District of Columbia offered another stunner.

During a sentencing hearing for Trump's former national security adviser, he excoriated Michael Flynn as having "sold out" his country for lying to Mueller's investigators about his communications with Russia's top diplomat in the United States. Flynn's sentencing was then abruptly postponed until at least March so that the judge could further assess his cooperation with prosecutors.

Trump, through it all, has repeatedly called Mueller's inquiry a "hoax" and "witch hunt" and insisted his campaign did not collude with Russia to win the election against Democrat Hillary Clinton.

"The Russian Collusion fabrication is the greatest Hoax in the history of American politics. The only Russian Collusion was with Hillary and the Democrats!" Trump tweeted on Sunday.

And Trump's denials concerning ties with Russia date to the early days of his administration.

“I don’t know Putin, have no deals in Russia,” the president wrote on Twitter on Feb. 7, 2017.

Mueller has kept a tight lid on his investigation and whether he has found any evidence of collusion by the Trump campaign with Russia is still far from clear. There is growing speculation that Mueller could wrap up his inquiry as early as mid-February, but the special counsel has not made public his timetable.

Meanwhile, the other federal investigations continue to grind on as Trump has stepped up his attacks on prosecutors and accused them of political motivations.

Yet one thing is clear: Several of Trump's denials concerning his connections to Russia and his efforts to bury damaging information during his campaign have been undercut by revelations in the various probes.

Here is a look at the drumbeat of recent revelations and their significance for the ongoing investigations:

Michael Cohen details Moscow Project

Throughout the campaign and into his presidency, Trump vehemently denied that he had any business interests in Russia.

Trump not only rejected any coordination between his campaign and the Kremlin but his repeated dismissal of financial ties to Moscow and potential business ventures there became one of Trump’s go-to catchphrases – "I have nothing to do with Russia" – as familiar as "Crooked Hillary" or "Lyin' Ted."

So when Mueller disclosed in court documents in early December how Cohen worked to conceal the president’s long-running interest in a Moscow tower project, the revelations eviscerated Trump’s blanket denials.

As early as November 2015, just five months after Trump launched his presidential bid, Russians were reaching out to Trump – through Cohen – with offers to boost the fortunes of the Moscow development, a vehicle that one of the Russians said could also provide the campaign with “political synergy.”

Cohen, according to court documents, was juggling separate offers from well-connected Russians at the time, seeking to arrange a meeting between Trump and Russian President Vladimir Putin.

One contact, described as a “trusted person” in the Russian government, promised that a Trump-Putin meeting could have a “phenomenal” influence on pushing the tower project and Trump’s political ambitions.

The person, who was not identified in the documents, went further, suggesting there was “no bigger warranty in any project than consent of (Putin).”

Despite the apparent assurances, Trump’s lawyer never followed up because he was “working on the Moscow Project with a different individual who Cohen understood to have his own connections to the Russian government.”

As Trump connections to Russia became an increasing risk to the campaign, according to court documents, Cohen lied about the back-channel Russia discussions when he told the Senate and House Intelligence committees that all discussions about a Trump tower development in Moscow had ceased in January 2016.

In fact, prosecutors have asserted that the project was discussed on multiple occasions within the Trump company. As late as June 2016 – in the heat of the campaign and as Trump continued to deny any links to Russia – efforts to obtain Russia’s approval for the project continued while Trump and family members were briefed on the progress.

In a May 4, 2016, email exchange with an Trump Organization official, who was not identified in court records, Cohen discussed traveling to Russia to advance the project before the Republican Convention in Cleveland in July, with the hope of arranging a separate subsequent trip by Trump.

"My trip before Cleveland; (Trump) once he becomes the nominee," Cohen said in the email.By June, Trump was heading into the convention as the presumptive nominee of the party where he secured the formal nomination.

Theefforts to conceal the work were designed to “minimize links between the Moscow project and Trump and give the false impression that the Moscow project ended before the Iowa caucus and the very first primary in hopes of limiting the ongoing Russia investigations,” prosecutors said.

Trump and his attorney, Rudy Giuliani, have asserted there was nothing illegal about seeking private business opportunities in Moscow, since his presidential bid at the time was far from assured.

Maria Butina works as Russian agent

Maria Butina, 30, illustrated that Russian efforts to influence the Trump campaign were brazen and went straight to the top.

Separate examples featured Trump campaign officials conferring with Russians. In June 2016, campaign chairman Paul Manafort, son Donald Trump Jr. and son-in-law Jared Kushner met Russians in Trump Tower to get information about Democratic rival Hillary Clinton. Meanwhile that spring, George Papadopoulos, a foreign-policy adviser to Trump's campaign, was busily trying to line up a Trump-Putin meeting. He finished two weeks in prison earlier this month for lying to FBI investigators about his Russian contacts.

Butina's continuing cooperation with investigators is a wild card among the myriad investigations that shadow Trump’s presidency. She was prosecuted by the U.S. Attorney's Office for the District of Columbia rather than by Mueller's team.

But her plea agreement described a multi-year conspiracy aimed to influence people and political organizations, including the National Rifle Association and the Republican Party. She reported her progress to top Russian officials, according to the agreement. Russian Foreign Minister Sergey Lavrov, who has met with Trump in the Oval Office, has called Butina a "political prisoner" who was jailed to "make her admit to something that she most probably did not commit," according to the Russian news agency Tass.

Butina's open-ended cooperation agreement calls for meeting with prosecutors in D.C. and Northern Virginia, according to a confidential court agreement that was made public briefly Friday, according to The Washington Post and CNN.

In March 2015, Butina drafted a proposal titled “Description of the Diplomacy Project,” according to the plea agreement she swore was true. She criticized official government channels and suggested using unofficial channels to influence U.S. foreign policy through individuals and groups such as the NRA.

Butina sent a Google-translated draft of the proposal to Republican political operative Paul Erickson for advice. He has not been charged in the episode.

She then sent her proposed budget – initially $125,000 – to a Russian official and others. The description of the official, a former first deputy chairman of the Russian Federation council and now a deputy governor of the Russian Central Bank, matches Alexander Torshin.

Butina’s efforts led to contacts. In July 2015, she asked Trump at the FreedomFest conference what his policy would be toward Russia and whether he supported sanctions the Obama administration and European Union imposed over Russian intervention in Ukraine.

“I believe I would get along very nicely with Putin, OK?” Trump replied. “I don’t think you’d need the sanctions,” Trump added. “I think we would get along very, very well.”

Trump hired Manafort the next year as his campaign chairman. Manafort now awaits sentencing for conspiracy, banking and tax convictions stemming from his work with a pro-Russia faction in Ukraine from 2006 to 2015.

A draft of the Republican platform at the Cleveland convention in July 2016 contained language for arming Ukraine against Russia. But the version ultimately approved softened the language to say America would provide “appropriate assistance” to Ukraine and “greater coordination with NATO defense planning.” Trump denied urging the change.

"I wasn’t involved in that,” Trump told ABC News at the time. Mueller has asked Trump about the platform change, according to ABC.

During this period, Butina was building her contacts. In December 2015, her advocacy group “Right to Bear Arms” invited NRA officials to Moscow to meet high-level officials. “We should let them express their gratitude now, we will put pressure on them quietly later,” Butina wrote in a message to Torshin, according to the plea agreement.

In May 2016, she wrote Torshin a note explaining why he should attend the annual NRA meeting in Louisville, Kentucky, where the group endorsed Trump – because he could meet political candidates. Torshin met Donald Trump Jr. at a dinner at the convention, but Trump Jr. denied any quid pro quo between the campaign and Russia. "None at all," Trump Jr. told the Senate Judiciary Committee.

In February 2017, she helped organize a Russian delegation – with members “hand-picked by (Torshin) and me,” according to the plea agreement – to the National Prayer Breakfast where Trump spoke during his first weeks in office. “Reaction to the delegation’s presence in America will be relayed DIRECTLY” to Putin and Lavrov, Erickson wrote in an email copied to Butina.

U.S. District Judge Tanya Chutkan will evaluate Butina’s cooperation Feb. 12 before sentencing at a later date. Butina faces up to five years in prison, but defense lawyers have said guidelines call for six months.

David Pecker kills stories about Trump

At the same time Trump’s aides began to field outreach from Russians, they opened a line of communication with another potential ally: The National Enquirer.

In August 2015, Cohen and “one or more members” of Trump’s nascent presidential campaign met privately with David Pecker, the chief executive of the Enquirer’s parent company, American Media Inc., federal prosecutors and lawyers for the company said n in an agreement sparing it from prosecution. On the table was what to do with negative stories about the tycoon whose life had long been the stuff of tabloid intrigue.

This time, the tabloid was interested in something else. Pecker told Cohen and the campaign that AMI could “deal with negative stories” about Trump’s relationships with women by tracking them down and paying for the rights to those stories so that neither the Enquirer nor anyone else would publish them. In effect, it was an effort to buy the silence of any woman who might come forward during the campaign.

Federal prosecutors in New York have said the arrangement violated campaign finance laws that limit how much people and companies can spend to influence an election. Cohen later pleaded guilty to two campaign finance violations and seven other felonies. He and the Justice Department have separately said Trump directed him to arrange the illegal payments, putting the president at the center of another criminal investigation.

Nearly a year passed before anything came of the arrangement.

In the interim, the Enquirer fawned over Trump, with front-page splashes about his Manhattan penthouse and an editorial declaring: “Only Trump has the guts to stand up to foreign leaders like Vladimir Putin – and gain their respect!” And it stomped his political rivals, falsely diagnosing Hillary Clinton with liver cancer and two strokes and suggesting that the father of Republican rival Sen. Ted Cruz had participated in the murder of President John F. Kennedy.

In June 2016, a lawyer for a former Playboy playmate named Karen McDougal contacted an Enquirer editor with an offer to tell the tabloid about what she said was an extramarital affair she had carried on with Trump not long after the birth of his youngest son, prosecutors and AMI said in their agreement. Pecker alerted Cohen. And the editor, whom prosecutors didn’t name, started negotiating to buy the rights to McDougal’s story.

In August, the tabloid paid her $150,000. In return, she signed over rights to her story of a relationship with “any then-married man.” Prosecutors and AMI said the sum was “substantially more” than the Enquirer would ordinarily pay for such a story, but Cohen had promised to repay it. And besides, the company agreed, its “principal purpose in entering into the agreement was to suppress the model’s story so as to prevent it from influencing the election.”

By early fall, Cohen tried to buy the rights from AMI. The company hired a consultant, who set up a shell company that could sell them to Cohen, along with a false invoice for “advisory services.” But Pecker reneged after the deal was signed. Instead, AMI had McDougal write for OK! Magazine and Star Magazine and put her on the cover of the fitness magazine Hers with an invitation to “learn her secrets to ageless beauty.”

That month, an agent for Stephanie Clifford, a pornographic film actress who goes by Stormy Daniels, contacted the Enquirer to say she too had a story to tell about a sexual affair with Trump. The tabloid again alerted Cohen, who began negotiating to pay her $130,000 to keep silent, the Justice Department said in court filings urging a judge to put Cohen in prison. The deal languished for weeks until Pecker alerted Cohen that Daniels was close to selling her story to someone else.

The next day, Cohen set up a shell company in Delaware and borrowed $130,000 to pay Clifford, according to court records. The Trump Organization reimbursed him for the payment, plus another $50,000 for what he described as “tech services for the campaign.” Then it doubled the sum and threw in a $60,000 bonus, according to court filings by prosecutors.

A federal judge sentenced Cohen on Dec. 12 to three years in federal prison for the campaign finance violations and other charges, including lying to Congress about Trump's plans to build a tower in Moscow.

"Time and time again I felt it was my duty to cover up his dirty deeds rather than to listen to my own inner voice and my moral compass," Cohen told the judge. "My weakness can be characterized as a blind loyalty to Donald Trump, and I was weak for not having the strength to question and to refuse his demands."

“While many Americans who desired a particular outcome to the election knocked on doors, toiled at phone banks, or found any number of other legal ways to make their voices heard, Cohen sought to influence the election from the shadows,” prosecutors wrote. In doing so, they said, “Cohen deceived the voting public by hiding alleged facts that he believed would have had a substantial effect on the election.”

Michael Flynn and Russia

Not since the scope of the Russia inquiry was publicly acknowledged in March 2017 by then-FBI Director James Comey – and later taken over by Mueller – have the interactions of a former Trump administration official with Russians been described in such stark terms in a federal courtroom.

Yet on Dec. 18, when former national security adviser Michael Flynn was preparing to be sentenced for lying to the FBI about his pre-inaugural communications with Russian ambassador Sergey Kislyak, U.S. District Judge Emmet Sullivan delivered a stunner.

Sullivan characterized the conduct of the retired three-star Army general, who last year pleaded guilty as part of a cooperation agreement with the government, as no less than a national betrayal.

“I’m going to be frank with you,” the judge told a grim-faced Flynn. “This is a very serious offense. It involves making false statement to the FBI on the premises of the White House in the West Wing!”

For the combat veteran and career military officer, what came next may have been more painful than the prospect of any prison term, as the judge motioned to the American flag and asserted that Flynn’s actions had “undermined” all it symbolizes.

Sullivan ultimately agreed to postpone Flynn’s sentencing until his cooperation with prosecutors is complete. But the searing rebuke and collapse of the sentencing hearing reverberated far beyond the courtroom.

The White House, which was closely monitoring the hearing, was caught off guard.

Trump spokeswoman Sarah Sanders, in a briefing shortly after Flynn’s court appearance, stuck to the administration’s disputed claim that the national security adviser was somehow “ambushed” by FBI agents during the January 2017 interview when Flynn falsely claimed that he had not discussed U.S. sanctions against Russia with ambassador Kislyak.

Flynn and his attorneys flatly rejected that notion during the hearing Tuesday, where Sullivan made clear that Flynn stood a better chance of avoiding a prison term if he continued to cooperate with prosecutors.

Mueller’s team had already recommended Flynn serve no prison time because of his extensive cooperation with investigators Mueller’s team. Flynn, 60, has met with investigators 19 times since entering his plea last year.

Yet the judge’s admonition raised the prospect that Flynn may have more to give. Just how much and the implications of any additional assistance were unclear.

Flynn’s cooperation in at least one other criminal case was revealed Monday when two of the general’s former business associates were charged with illegal lobbying on behalf of the Turkish government.

Robert Kelner, Flynn’s attorney, said Tuesday that it was likely that Flynn would be called to testify at any future trial. At the same time, prosecutors acknowledged that Flynn likely would have faced additional criminal charges had he not agreed to cooperate with Mueller’s team.

It is immediately unclear what Flynn has provided investigators related to any additional Russia contacts, both during the administration and the campaign.

But few apart from Flynn, who also served as a national security adviser to the campaign before joining the administration, had access to information about interactions with other governments during the campaign, transition and early days of the Trump government.

Mueller’s office said Flynn’s lies about his interactions with Russia’s ambassador were important because they raised “the question of why he was lying to the FBI, the vice president, and others.”

And they hinted he may be helping them find the answers, saying in a previous court filing that among the subjects on which he was cooperating were interactions between Trump’s campaign and transition team and the Russians, noting that several members of the transition team publicly repeated his lies. Flynn had more to say on the subject, but prosecutors left it blacked out in their public court filing.

Sullivan is set to reassess Flynn’s cooperation in March.

“The more you assist the government, the more you help yourself at time of sentencing,” Sullivan said. “I’m not promising anything; the court was just being upfront with you.”

Mueller's machine grinds on

As Flynn continues his cooperation, so do Butina, Cohen and Pecker.

While they hardly represent the universe of witnesses Mueller and prosecutors in D.C., Virginia and New York are leaning on to understand the scope of Russia's intervention and Trump's political operations, it is now clear that they are key to shaping the contours of the continuing investigation.

Where it all ends largely rests in an all-but-closed shop that Mueller has run since taking over the investigation after Comey's May 2017 firing.

Outside of Mueller's offices, however, the path forward has been blurred.

Acting Attorney General Matthew Whitaker, appointed in the wake of Attorney General Jeff Sessions' firing in November, decided not to recuse himself from oversight of the investigation, even though a Justice ethics officer recommended that he step away because of past public criticisms of the probe.

Former Attorney General William Barr, nominated by Trump as the permanent successor to Sessions, also has drawn fire for his own criticism of the Mueller probe in a memo he sent earlier this year to the Justice Department.

However, during a late December news briefing, Deputy Attorney General Rod Rosenstein offered assurances that the inquiry was in good hands,

"Whether it's Bob Mueller or Rod Rosenstein or Matt Whitaker or Bill Barr, that investigation is going to be handled appropriately by the Department of Justice," Rosenstein told reporters on Dec. 20.