Transcript for Russia investigation seeks first charges

New developments overnight in Washington. Sources confirming to ABC news that special counsel Robert Mueller and his team have field the first indictment in the Russia investigation. Who could be the target? David Wright is at the white house. Good morning to you. Reporter: Good morning, Dan and Cecilia, this white house is girding for battle this morning. They know that the first indictment is likely to drop tomorrow in the Russia probe. And like us, they're not sure who is about to be charged. Call it ruche Yan roulette. The first criminal charges imminent in the investigation of Russian meddling in the 2016 election and possible collusion by trump associates. We didn't win because of Russia. We won because of you. Reporter: ABC news has confirmed that a senior prosecutor from Robert Mueller's office, who specializes in fraud cases, was at the federal courthouse in Washington Friday, where the grand jury was in session. Mueller's team field papers with the court. And sources tell ABC news an arrest could come as soon as tomorrow. But who? The special counsel's office declines to say. ABC news reached out to former trump campaign chair Paul manafort's legal team. They say he has no indication that any charges against him could be imminent. We reached out to former national security adviser Mike Flynn's team. No spont. The president himz as long dismissed the investigation as a politically motivated witch hunt. The whole Russia thing was an excuse for the Democrats. Reporter: His allies are on the warpath. Former campaign director Corey Lewandowski on "Fox & friends." The speculation is so insane. We should be focused on the lied of the Clinton administration. Reporter: Roger stone took to Twitter to call out CNN. His language so derogatory, and in some cases, homophobic, that Twitter suspended him. In an interview with "The new York Times" before news of the indictm-nt broke, the white house lawyer said the president is not worried. The president has no concerns in terms of any impact as to what happens to them on his campaign or on the white house. Reporter: Again, that interview given before news of this indictment broke. As for Roger stone, he's taking his Twitter suspension as a badge of honor. Texting our own Katherine folders overnight saying sometimes the stark truth offends some people. And stone vowed terminator style, I'll be back. Dan and Cecilia? I'm sure he will. He will. David, thank you.

This transcript has been automatically generated and may not be 100% accurate.