(CNN) Special Counsel Robert Mueller's plea deal Friday with President Donald Trump's former national security adviser signaled that Mueller is closing in on senior officials of the 2016 Trump campaign, heightening the conflict between the two leading players in America's post-election Russia drama.

Trump tried to staunch the Russia investigation on multiple fronts.

An overriding question is whether the new revelations increase the chances that Trump tries to get rid of Mueller, as he did last May when he sacked FBI Director James Comey, who first led the investigation into possible Trump campaign ties to Russian interference in the election.

Or would the President attempt to get ahead of Mueller by pardoning associates, including former Trump national security adviser Michael Flynn, who on Friday pleaded guilty to lying to the FBI about conversations with Russia's ambassador and disclosed he is cooperating with Mueller.

Not only is Flynn the first person inside the Trump administration to be charged by Mueller, he also is the one individual who Trump apparently was trying to shield. Former FBI director Comey testified on Capitol Hill in June that Trump had pulled him aside and said, " 'I hope you can see your way clear to letting this go, to letting Flynn go. He is a good guy. I hope you can let this go.' "

Read More