Because it is almost certain that the Supreme court would either go 3 to 5 against President Trump or 4 to 4 to let the lower court ruling stand.
That's why the Gorsuch nomination has become more urgent and important.
And that's why democrats will do everything they possibly can to kill the nomination in order to hand Trump a permanent defeat on the ban.
They are more interested in winning a olitical battle than in National Security.
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Have the events surrounding Flynn now emboldened the Never Trump Republicans to join forces with the Democrats to defeat Gorsuch, even if the nuclear option is used? Blood is in the water.