The more fun piece of fiction is that the Dems are trying to remove Trump. The Dems are simply following the CIA's lead; they are the ones trying to remove Trump.
Considering the facts that the Dems do not have the power to actually remove Trump and that the H.R. (regardless of which party is in the majority) only has th power to impeach a president not remove him...
I think it would be more accurate to say that the Dems are trying to find enough facts (or a set of facts) that Trump has committed "high crimes or misdemeanors" in hopes that it will:
1. Massively embarrass Trump
2. Force the GOP controlled Senate to take the next step towards removal. (See below)
3. Convince most Americans to vote Trump out of office. (Note: This is the most likely goal of the Dems.)
The impeachment of Trump, while it would not remove him from office, it would force the GOP members of the Senate to go on the record of supporting Trump or removing him.
A. If te facts were somehow overwhelming and truly called for Trump to be removed, the GOP Senators might put their re-election possibilities at risk by not removing Trump.
B. If the facts were not somehow overwhelming (i.e. the facts were questionable), than the GOP Senators would be foolish to remove Trump as that would definitely put their re-election possibilities at risk.
The point being that the Dems cannot remove Trump, they can only hope to set forth a situation that either compels the GOP to remove Trump or compel the American voter to vote Trump out.
Now, as to the CIA... they are not substantively involved in this. If they wanted Trump out, he would be dead already... or in a coma... or incapacitated... or... well, I think you get the point.