For the last couple of days, I've been writing about Susan Collins and her attempt to craft the Republicans' Obamacare replacement. In a normal circumstance, she'd run the show.
In political science, she is basically what we'd call "the pivotal voter." Array everyone along a line, based on ideology, and whoever is at the relevant pivot point to get over the relevant hurdle (majority threshold, filibuster threshold, whatever) has a lot of power. Collins may not be the exact pivotal voter in the Senate, but she is close to it. And, she has basically taken leadership of a pivotal faction. If she says, "screw you guys, I'm going home," Obamacare stays in place. So, she should set the terms. She should be able to tell everybody in the Senate and the House to accept Collins-Cassidy and call it a done deal. She should be in the same situation as Ben Nelson and Mary Landrieu in 2010 when the ACA passed.*
Why isn't she, necessarily?
That's why. There is a large, and dominant faction of hardliners in the Republican Party, willing to walk away from nearly complete victory if it isn't 100% victory. John Boehner was a pretty damned effective Speaker of the House, in my opinion. I'm not shy in my praise for him. But, he was run out of town by the people in his own caucus whom he called "knuckleheads." Why? Short version: he couldn't force Obama to repeal Obamacare by stomping his feet and holding his breath until his face turned blue. For that sin, a truly brilliant Speaker (yes, I liked Boehner) was given the bum's rush.
And there are a lot of those knuckleheads in the House of Representatives today. And if they refuse to accept Collins-Cassidy, Obamacare stays in place.
Collins' bargaining power rests on the premise that everyone in the Republican Party understands that they need to accept her position. Among the Democrats in 2010, that was true with respect to Nelson and Landrieu. Even Bernie Sanders was smarter than the knuckleheads, and that dude is a fucking moron. (Wow, it's been a long time since I've picked on him...)
So, yes, Collins could demand that the party accept Collins-Cassidy or lose her vote to repeal Obamacare. She hasn't gone that far yet, but she could. If she did, would it work? I don't know. I wouldn't bet on it. Why not? Well...
In a normal party, Collins would be the belle of the ball. But in a normal party, John Boehner would still be Speaker, Donald Trump wouldn't have gotten that nomination, and they would have accepted Obama's offer of far bigger spending cuts, including switching to chained-CPI for Social Security in exchange for small tax increases back in 2011.
What will happen with Obamacare and Collins-Cassidy? I have no idea.
*Of course, Nelson and Landrieu did eventually get screwed, but that's another story...