Why Is The House Still Trying To Pass The AHCA?

Can someone please explain to me what is the political calculation driving the House to try to ram through an unpopular health care bill that they know will go nowhere in the Senate. The revised bill will get the same horrendous CBO score as before and, for potentially vulnerable GOP members, the Democratic attack ads virtually write themselves. With the most recent special elections showing an over 10% swing toward Democrats, that would mean over 100 Republicans would be in danger in 2018 if that trend holds. So what is driving the GOP?

The original idea was that ACA repeal would create a $1 trillion tax cut that could then be used as the baseline for further tax reform and greater tax cuts in for the 2018 budget. But, if Republicans know this bill will never fly in the Senate, then that can't be the reason for continuing to try to pass the AHCA. Is it Paul Ryan who sees this as a way to show that his leadership is not a failure and save his job as Speaker? Is it the House Freedom Caucus who Trump blamed for the original AHCA defeat trying to avoid primary challenges in 2018? And what are some of the House moderates thinking?

As Chris Hayes pointed out last night, the tax credits that the AHCA will use to replace the Obamacare subsidies can not be used to purchase health insurance plans that cover abortion. That was in the original bill and, as far as I know and correct me if I'm wrong, that provision has not been changed with any of the recent amendments. State law in California requires that abortion be covered and it is part of the minimal plan in New York. In Massachusetts, abortion that is considered medically necessary must be covered.

Are Republican moderates in New York and California, who are almost by definition considered vulnerable, going to vote to pass the AHCA with this provision in it, even if it dies in the Senate. According to the latest Huffington Post whip count for this week's supposed vote on the AHCA, there are two GOP House members from California who lean no, Paul Cook and David Valadao. There are four members who are undecided, two from California and two for New York, Steve Knight, Ed Royce, John Faso, and Elise Stefanik. And there are two who lean yes, Darrell Issa and Peter King.
Three of those Republicans, Steve Knight, John Faso, and Darrell Issa, won by less than 10% in 2016. Two others had margins that were around 15%.

I still have no idea what the Republicans in the House are thinking. Is this simply an attempt at CYA for the conservatives? Are they caving in to pressure from Trump? Is Paul Ryan driving the issue? I don't have a clue. What I do know is that the longer the House and Donald Trump take talking about health care and still getting nothing done is another day for Democrats to rally their base, another day to display GOP failure, and another day wasted for the rest of their legislative agenda.