Dan Coats or Susan Gordon, the Director of National Intelligence, (DNI) likely is the whistleblower. Now this is based upon inferences and timing, but it makes sense. Coats and Gordon must be called before Congress in order to develop the facts. Even if I am wrong, they certainly would have much insight into the matter as they certainly resigned, forced out by Trump, over Trump’s statements in the telephone call with the Ukrainian president.

TIMELINE:

Starting in April, Trump instructs Giuliani to influence Ukraine to find dirt on Biden and son. Giuliani waived promises and who knows what else before Ukraine’s new administration.

Congress approves a $250M military aid package for this fiscal year, 2019. Trump holds up the aid with the excuse that the aid is being reviewed. Ukraine needs the money to resist the Russian occupation of part of its land.

July 24 Mueller testified before Congress deflating hopes of any ramp up towards Trump’s impeachment. Trump is feeling pretty good. Mueller did a terrible job carefully avoiding any Comey type political impact but he made one trying to avoid one. Next day July 25, Trump is emboldened and feeling invincible and calls Ukrainian president to strongly and repeatedly urge him to investigate the Biden family. The military aid is still frozen. Only three days later, on July 28, Trump announces Coats is leaving and Coats walks into a meeting and tells his deputy Susan Gordon that she has to resign too. These resignations are certainly on orders from Trump. The resignations are to be effective on August 15. On August 12, just three days before the Coats and Gordon resignations take effect, the whistleblower complaint was lodged with the Inspector General of Intelligence in compliance with the whistleblower law. Interesting timing. August 15, Coats and Gordon resign as DNI and deputy DNI. Maguire is sworn in as acting DNI. August 26, the whistleblower complaint forwarded to acting DNI (appointed to protect Trump's bribery?) September 2, Maguire misses deadline to forward the whistleblower complaint to Congress thereby violating a very clearly written law. He did this based upon the opinion of Trump’s personal attorney, you know, Barr, the Attorney General of the United States. As DNI and Deputy DNI, Coats and Gordon would be the most likely people to have access to the conversation with the foreign president whose nation was involved in a war with Russia. It is becoming very clear that Coats and/or Gordon had it out with Trump after his call with Ukraine's president, arguing that what Trump said and promised to Ukraine’s new president was not only inappropriate but illegal conduct as well. Their argument certainly caused fireworks. There was probably a discussion regarding their obligation to report his illegal conduct relating to national security. Trump would take their conduct as mafia disloyalty that he could not allow and as a danger to his penal interests. Coats and Gordon were fired for this. In response to the firing, and as a way to inform Congress of the impeachable offense, the whistleblower complaint was filed by either Coats or Gordon.