Trump's Supreme Court nominee, Neil Gorsuch, just got the last "no" it needed so the Democrats can meet the vote threshold to filibuster his nomination. Claire McCaskill (D-MO) wrote a Medium post about her decision today:
I remain very worried about our polarized politics and what the future will bring, since I'm certain we will have a Senate rule change that will usher in more extreme judges in the future.
Why it matters: Republicans will now have to get rid of the 60-vote filibuster threshold for judges, or allow Gorsuch's nomination to fail.