Where things stand with special counsel Mueller's Russia probe

— -- Department of Justice–appointed special counsel Robert Mueller is conducting what is generally called a preliminary inquiry into possible obstruction of justice involving President Donald Trump, as it pertains to his broader investigation into Russian meddling in the U.S. presidential election.

Mueller was tasked with overseeing the investigation in May. He and his team are currently assessing former FBI director James Comey's recent testimony before the Senate Intelligence Committee, reviewing Comey’s memos documenting his encounters with Trump, and preparing to interview certain administration officials — such as Director of National Intelligence Dan Coats and National Security Agency Director Mike Rogers — regarding press accounts of comments the president allegedly made to them about the Russia probe.

At some point, Mueller may wish to interview FBI senior leadership about their meetings with Comey regarding Trump, though it's unclear if this has already taken place.

A full-scale investigation has not yet been launched, although preliminary work is clearly being done, according to sources familiar with the process.

An assessment of evidence and circumstances will be completed before a final decision is made to launch an investigation of the president of the United States regarding potential obstruction of justice.

Comey said under oath during his much-anticipated Senate hearing earlier this month that he believes he was fired because of the Russia investigation.

"Guess I don’t know for sure. I believe the — I take the president at his word, that I was fired because of the Russia investigation. Something about the way I was conducting it, the president felt, created pressure on him that he wanted to relieve,” Comey told the Senate Select Intelligence Committee.

Comey also told the Senate that he intentionally leaked his contemporaneous memos detailing his conversations with Trump in order to prompt the appointment of a special counsel.

Any kind of alleged effort to interfere in an investigation could potentially lead to an obstruction of justice investigation targeting the president and his aides.

Deputy Attorney General Rod Rosenstein, who has oversight authority over the special counsel investigation, has told colleagues he may have to recuse himself. A decision on recusal is not imminent, according to sources familiar with his thinking.

Rosenstein is overseeing Mueller's work since Attorney General Jeff Sessions recused himself from the investigation because of his ties and participation with the 2016 Trump campaign.

The deputy attorney general could become a witness if the circumstances of Comey’s firing are considered part of an obstruction investigation.

To indicate that a full scale investigation has been launched, all eyes will be on Rosenstein's actions, as well as evidence of a grand jury subpoenaing key White House aides with a focus on Trump. Another key will be Mueller's assessment of Comey allegation that Trump tried to get him to stop the investigation of former National Security Advisor Michael Flynn.