ANALYSIS: To begin change, Republicans must accept the GOP is not Reagan's party anymore Once Republicans accept this, then they can counter the Trump-Bannon takeover.

 -- Quiz: Please tell me if the following candidate could win a Republican primary in today's GOP. This candidate is for expansive free trade, amnesty for undocumented folks in America illegally, raised taxes multiple times in a series of compromises with Democrats, signed a law liberalizing access to abortion, sold weapons to Iran and made his living in Hollywood.

Could this person win among GOP primary voters today? Anyone understanding today's Republican Party would answer with a resounding no. And the candidate described was Ronald Reagan.

During the GOP presidential primaries of 2016, I made the argument that Reagan would have a very difficult time winning in today's GOP. Last Sunday on "This Week," I said Reagan couldn't win among GOP voters, who have overwhelmingly adopted Trumpism, that the Republican Party as we have known it is gone and the only way to find it was to be in touch with H.G. Wells and get in a time machine.

This was all before GOP Sens. Bob Corker and Jeff Flake made full assaults this week on the president and the Trump–Steve Bannon takeover of the GOP, as both senators said they decided not to run for re-election because they didn't feel the party fit them anymore. The development is astounding and telling, confirming my speculation on the direction of our politics.

The fascinating turn here is that Corker's and Flake's fight isn't an ideological one; they aren't being driven out of the Trump GOP circle because they aren't conservative enough. To the contrary, they are more conservative than him on nearly every single issue. They are being driven away because they believe that, in our country, there ought to be certain norms of behavior that are honored and expected, that ideals of civility and respect for one another, thoughtfulness and public service should be honored in and demanded of our leaders.

The Trump-Bannon takeover of the GOP and Republican voters' encouragement of this has little to do with conservatism or American ideals. It has more to do with isolationism, division, fear-based appeals, anger at fictitious enemies, settling scores and nationalism.

This seems to be the opposite of Reagan's ideals. And it has caused many conservative leaders around the country — including Corker, Flake and Sen. John McCain — to reject this type of politics and governance.

Yes, one could make an argument that John F. Kennedy would have a very difficult time winning in today's Democratic primaries, and I made just that point a few years ago in examining the changing ideological landscape of Democratic voters.

However, today is for confronting what has become of the GOP, which probably wouldn't nominate either of the Bushes, Bob Dole or, for sure, McCain. That is a huge concern for America.

I have told my Republican friends that if they truly want to resist what is happening in America today, the best route to reform isn't likely in winning GOP primaries or waiting for Trump to exit the scene. It is to embrace independent candidates for office or support Democrats in the short term in order to begin a return to American ideals and norms we should all embrace. I have told those friends the Republican Party they want or used to belong to no longer exists and they need to come to terms with that.

Elizabeth Kubler-Ross laid out five stages of grief: denial, anger, bargaining, depression and acceptance. It seems many Republicans are in the denial, anger and bargaining phases.

To be a force in politics, Republicans who are resistant to the party now captured by Trump and Bannon need to get quickly out of depression and move to acceptance. Once they accept that the party as they knew it — or want it to be — is gone, then those Republicans can be a force in governance by becoming independents or reaching temporary alliances with the Democrats.

And to my GOP friends: Once you get to acceptance of the current reality of your party, you will be much more at peace and can begin taking constructive steps, as opposed to denying reality or mourning the loss of your Grand Old Party that encompassed Abraham Lincoln, Teddy Roosevelt and Reagan. The shining city on a hill is still achievable, but you won't get there in a time machine.

Matthew Dowd is an ABC News analyst and special correspondent. Opinions expressed in this column do not necessarily reflect the views of ABC News.