c. The White House made multiple efforts to hide evidence of the Ukrainian effort. There has been an obvious coverup.
5. The White House must cooperate. The Trump Administration is between the proverbial "rock and a hard place." If they fully cooperate it will move the House inquiry closer to a vote. If they don't cooperate, the House Democrats will have further ammunition for their "cover up/obstruction" charges.
The whistleblower report contains evidence of the equivalent of the infamous Nixon tapes. The report indicates:
"White House lawyers directed White House officials to 'remove the electronic transcript from the computer system in which such transcripts are typically stored' and place the word-for-word account on a server typically reserved for highly classified information, according to the complaint... White House officials said this was 'not the first time' that a presidential transcript was placed into this codeword-level system to shield politically sensitive information."
The House Intelligence committee must be granted access to this special server. If necessary, they will have to go to the Supreme Court to obtain this information.
6. The House Vote Has to Attract Some Republican Support. If the House vote was held today, it would pass but with only Democratic support. If the impeachment inquiry is quick, focussed, and produces overwhelming evidence of Trump's guilt, then it should attract the votes of some Republican House members -- certainly those in swing districts.
It's possible to bring the House impeachment process to a vote before the end of the year. Let's worry about the Senate process in 2020.