SchifftyEyes keeps moving the goal posts. Now he claims they don't need a "whistleblower" as a witness. He probably thinks that can impeach Trump based on his own parody of Trump's phone call.
I think this a strategy to drag this "inquiry" out with headlines and sensationalism in an attempt to damage Trump during the 2020 campaign.
But even if the House does vote articles of impeachment against Trump, it will stop dead in it's tracks in the Senate, his poll numbers will rise, fundraising will go through the roof and he will handily win reelection in 2020.
The Democrats are doing one of two things--if they have enough votes, they're going to drag out the "impeachment inquiry" as long as they can to inflict damage on Trump, re-election-wise. This may or may not be a good strategy.
The second thing is that they may yet still be whipping for votes to get a majority of Dems that will actually vote for impeachment. I don't think this is a slam dunk, and I think there's a real calculus going on to see if they can get through this process without losing their entire House majority.