House Speaker Nancy Pelosi has told friends that impeachment now feels unavoidable, according to someone who discussed it with her last night. She hates the politics of it, but has succumbed to the inevitability, the source says.

The bottom line: Trump’s decision to release the transcript of a call with the Ukrainian president doesn’t appear to have stopped Democrats’ march toward impeachment.

Here's where it stands:

On the merits, Pelosi now sees a potential necessity for impeachment even if she dislikes the political impact it could have.

One key factor driving Pelosi's thinking is that the White House so far has refused to turn over the whistleblower's complaint about Trump's actions — something it is required by law to do.

That's the argument Joe Biden will make this afternoon, per his campaign: that the White House's refusal to uphold the law would be a tipping point, regardless of the contents of his July 25 call with the Ukranian president.

Pelosi is letting freshman members count the votes within their caucus, which enables them to be responsible for their own fates and insulates Pelosi from later blame.

It also gives her room to create space for any vulnerable Democrats who aren't on board with impeachment — assuming they get past the necessary 218 votes needed to initiate formal proceedings.

As of today, 154 members of the caucus support impeachment, and that number is rapidly growing.

Several members, including Rep. John Lewis, one of the most influential members to resist endorsing impeachment, announced on Tuesday that they support impeachment proceedings against Trump.

Lewis' endorsement will likely open the floodgates for other progressive members and those within the Congressional Black Caucus to join him.

Several members have told Axios that Lewis would not publicly support impeachment if Pelosi had advised against it.

Worth noting: This is the last week the House is in session before recessing for two weeks. That could slow down the momentum for impeachment.

The bottom line: The White House still has a potential way to halt the escalating momentum for impeachment: turn over the whistleblower report.

If the White House refuses to turn over the report to Congress by Thursday, when acting Director of National Intelligence Joseph Maguire appears before the House Intelligence committee, than Democrats will likely feel forced to move ahead with an impeachment inquiry.

But if the White House turns over, it could potentially give Democratic leaders an exit ramp.

Go deeper: Which House Democrats currently support impeachment