President Mattis?

With each day, the scandal around the Trump administration and Russia grows. It is now a looming threat over the entire Republican party that could throw a large number of high ranking Republicans into impeachment, resignation, disgrace, or jail. Assuming that an impeachment process is initiated against the President, the US might not have a Vice President who can take over, because Mike Pence might well have been in on the collusion with Russia. In that case, looking at the succession order for the presidency, we see an interesting situation:

Next in line after Mike Pence is House speaker Paul Ryan. However, judging from his recent actions, he seems to be implicated in the cover-up. Senator Orrin Hatch was excluded from the recent closed briefing of the Senate Judiciary Committee by the FBI, so he seems to be somehow suspect as well. Rex Tillerson is one of the most questionable people in the Trump cabinet with his strong ties to Russian interests, and Steven Mnuchin is a member of Trump's inner circle, so he could be out as well.

The Russia connections now run so deep in the White House and in the Republican side of Congress that in case of an impeachment against Donald Trump, there is at least a remote possibility that we will see James Mattis, sixth in line, being offered the presidency. It's nothing but conjecture at the moment, but it doesn't sound nearly as impossible as it ought to. This says something about how serious the problems are for the Trump presidency.