(This article was first published on simon jackman's blog » R, and kindly contributed to R-bloggers)
A little bit of churn relative to the House’s 1st shot at this but otherwise a remarkably similar vote, with an estimated cutpoint almost at the same place; see some raw R output, below the fold, after the thumbnail…

y is the vote to take up the Senate amendments; yEarly is the previous go at this by the House:
table(y,yEarly,exclude=NULL)
yEarly
y 0 1 NA
0 206 6 0
1 8 211 0
NA 1 3 4
Probits of the votes against ideal points:
> coef(m1) (Intercept) x -0.7004063 -3.4044442 > coef(mEarly) (Intercept) x -0.7372492 -3.3910989
Cutpoints:
> -coef(m1)[1]/coef(m1)[2] (Intercept) -0.2057329 > -coef(mEarly)[1]/coef(mEarly)[2] (Intercept) -0.2174072
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