Washington (CNN) Another big exit from the Trump White House, a mystery of sorts about possible immigration policy twists, updates on congressional Russia investigations, two bellwether governor's races and Michael Bloomberg's war on soda -- it's all in this week's "Inside Politics" forecast.

1. Trump losing trusted aide, sounding board

Keith Schiller may not be a household name, but he is frequently in the background when you see photographs and video of President Trump. That won't be so for much longer -- and it is another White House departure that will remove a loyal player from the West Wing.

Schiller was a member of Trump's security team when he was a private citizen, a key player in his campaign team and at the White House. His role goes beyond security; Schiller is known to be among those to whom the President turns when he wants to chat -- or vent.

CNN's Sara Murray reports that having one less trusted person around raises questions about how the President will let off steam.

"We know this is a President who needs to vent, and sometimes he does that publicly on Twitter, sometimes he does that privately," Murray said.

"The President is losing another very trusted hand who can sort of moderate him, absorb some of the blowback behind the scenes when the President is frustrated."

2. State cases push Dreamer deadline -- is Sessions a quiet supporter of that pressure?

The White House is promising a decision Tuesday on the question of whether President Trump will keep a pledge to revoke temporary legal status the Obama administration extended to so-called Dreamers -- young people who were brought to this country illegally as children.

The pressure stems in part from state court cases addressing the issue.

Candidate Trump promised to immediately reverse the Obama policy, but as President he has at times suggested he was looking for some sort of compromise. The conservative Trump base is worried -- even more so now that recent White House personnel changes have left the President with an inner circle many conservatives don't trust on immigration and other issues.

Not all of the immigration hardliners are gone. The Atlantic's Molly Ball raised an intriguing question or two about the role of one -- Attorney General Jeff Sessions.

"The Department of Justice denies that Jeff Sessions has played any role in what the attorneys general are doing, but he has spoken approvingly about it," Ball said. "He has said he welcomes the administration being held accountable by the states and a lot of people involved in this issue in and out of the administration suspect that actually the attorney general is sort of behind the scenes encouraging this action."

3. Congress is back -- and the Russia investigations move to the President's inner circle

Congress is back to work this week -- and there are some big Russia meddling investigation moments on the horizon.

Among them: Donald Trump Jr. is scheduled to submit to a Senate interview about his June 2016 Trump Tower meeting with Russians who promised him dirt on Hillary Clinton.

The President's son is just one of the high-profile witnesses who will get attention from congressional investigations that faded a bit from the public eye during the summer. Karoun Demerjian of The Washington Post said most of the significant developments are likely to come on the Senate side.

"Congress coming back into town means things on the Russia probes kick back into gear," Demerjian said. "We're entering a phase where Trump's inner circle is coming to talk to members -- on the Senate side, at least -- for the first time."

4. Gubernatorial races could yield clues for 2018, 2020

We live in the age of perpetual campaigns, but Labor Day still is considered a traditional launching point for the final stretch of big elections.

This being 2017, there aren't House or Senate races on the ballot, except for a special election here and there. And the next presidential campaign isn't until 2020. But don't forget New Jersey and Virginia -- the two states that have odd-year gubernatorial elections.

Michael Shear of The New York Times said they could tell us a lot about the national mood headed into the midterms. "They'll provide an early clue of what voters are really thinking about all the craziness that we've endured for the last six, eight months," Shear said. "We've seen polls, obviously. We know a little bit about what the public thinks. But this is an opportunity to get an early sense of how the midterm elections next year will go."

5. Bloomberg spending big in soda wars

Michael Bloomberg's war on the Big Gulp is getting more expensive -- even in places where the former New York mayor has already won.

He increased ad spending in Cook County, Illinois, this past week for example -- bringing to $5 million his ad spending in the Chicago area, where the beverage industry is hoping to repeal a tax on soda and other sugary drinks. Bloomberg also has spent about $2 million recently on ads in Philadelphia, where the tax is already in effect.

The battle isn't just about the continued political fallout in communities where a "soda tax" has been enacted. Bloomberg wants other cities to follow suit -- arguing the tax will help fight childhood obesity and diabetes. But some of the politicians who have sided with Bloomberg have taken a political hit, and the beverage industry hopes to wound or defeat some of them -- to send a signal to politicians elsewhere.