President Donald Trump is busy tweeting about the probe. Lawmakers have continued their proxy fights over the issue. And a series of news reports have brought new angles to light.

Here's a breakdown of the latest twists, why they matter and what's next.

Unproven 'spy' saga continues

What happened: Trump continued hammering away at the Justice Department and the FBI over his unproven claim that a "spy" had been embedded in his campaign "for political purposes." No evidence has come to light to support Trump's claims, which are a distortion of reports that the FBI used a confidential source to investigate Russian outreach to people on the campaign.

Why it matters: The attacks resemble more of a public relations strategy than a legal one. Trump's attorney Rudy Giuliani The attacks resemble more of a public relations strategy than a legal one. Trump's attorney Rudy Giuliani admitted as much Sunday on CNN: "It is (for) the public opinion, because eventually the decision here is going to be impeach or not impeach."

Next steps: We're already seeing polls that say Republicans are losing faith in special counsel Robert Mueller, which suggests Trump's attacks are working with his base. Will this trend continue? But some Republicans think efforts to remove Mueller would cross a red line, as Arizona's Sen. Jeff Flake We're already seeing polls that say Republicans are losing faith in special counsel Robert Mueller, which suggests Trump's attacks are working with his base. Will this trend continue? But some Republicans think efforts to remove Mueller would cross a red line, as Arizona's Sen. Jeff Flake said Sunday on NBC's "Meet the Press."

Controversial DOJ briefings

What happened: Senior officials from the Justice Department and FBI gave two classified briefings to lawmakers about the confidential FBI source who aided the early Russia probe. Before the meetings began, White House chief of staff John Kelly and White House lawyer Emmet Flood spoke to the bipartisan groups of lawmakers, explaining that Trump wanted maximum transparency on the matter.

Why it matters: There was There was immediate backlash , primarily from Democrats, to the White House's involvement in meetings that were supposedly about congressional oversight. The stakes are high because Trump is the subject of the investigation that the briefing was about.

Next steps: Will Hill Republicans be satisfied? They demanded copies of FBI and Justice Department documents. If they don't get them, Republicans can pursue contempt of Congress charges or initiate impeachment proceedings against Deputy Attorney General Rod Rosenstein or FBI Director Christopher Wray.

Roger Stone in the spotlight

What happened: Mueller's team is probing the personal finances of Roger Stone, a longtime Trump ally who claimed ties to WikiLeaks during the 2016 campaign. Investigators have hauled some of Stone's associates to the grand jury and are asking about his finances and tax returns. CNN reported Mueller's team is probing the personal finances of Roger Stone, a longtime Trump ally who claimed ties to WikiLeaks during the 2016 campaign. Investigators have hauled some of Stone's associates to the grand jury and are asking about his finances and tax returns.

Why it matters: These developments suggest that Mueller's inquiry into Stone may have broadened beyond his conduct relating to Russian meddling. Stone says this means the prosecutors are running amok. But Mueller's mandate allows him to examine potential crimes he uncovers while investigating Russia.

Next steps: The looming question is: Will Stone face criminal charges? If he is indicted, Stone would be the fifth Trump associate charged in the Mueller investigation. And unlike some of the other Trump associates who pleaded guilty or are fighting charges, Stone has been close to Trump for decades.

A ditched date with Mueller

What happened: We learned last week that Trump's lawyers and Mueller's team had We learned last week that Trump's lawyers and Mueller's team had set a date and discussed logistics for Trump's high-stakes interview with investigators. It was set for January 27, but talks between the two sides eventually stalled and the President's team ultimately rejected the plan.

Why it matters: These new details show that Trump was closer than previously known to meeting Mueller. It also suggests that Mueller felt comfortable enough in late January with the progress of his investigation into potential obstruction of justice that he was ready to interview the President.

Next steps: It's still unclear whether Trump will agree to an interview with Mueller. If he does, how will it all go down? If he doesn't agree, will Mueller seek a subpoena for Trump's testimony? Giuliani told CNN on Sunday that he is OK with Trump doing a limited interview, but it "depends on how comfortable we are with their having an open mind and not having interpreted it wrongly already."

Another Trump Tower meeting

What happened: The New York Times reported Donald Trump Jr. met a group of well-connected businessmen at Trump Tower, months before the 2016 election, and was offered campaign help from a liaison for two Middle East governments that are top US allies: Saudi Arabia and the United Arab Emirates. Lawyers for the players involved said the meeting didn't lead to anything and denied that there had been any effort by foreign governments to influence the US election.

Why it matters: Trump Jr. is already under scrutiny for a separate Trump Tower meeting -- his June 2016 liaison with a group of Russians who supposedly had dirt on Democratic nominee Hillary Clinton. This news puts Trump Jr. in yet another room with foreign nationals seeking to meddle.