Say this for the dim bulbs of the GOP: They finally made a decision. It is now Marco Rubio or bust.

While spending months burning through mountains of money for next-to-nothing results, party leaders, candidates and their backers took comfort in the theory that Donald Trump was winning only because the Republican field was so large. With Rubio now designated the favorite son of the anti-Trump crowd, the theory will be tested Tuesday.

If Trump runs the table or anything close, it’s game over. Not just for Rubio, but also for the party’s entire establishment. Trump is a total disrupter, and the GOP would never be the same.

The slashing of the long knives that Rubio started last week will continue until the polls close. The baby-faced senator from Florida is on a feverish pace of interviews, rallies and attacks because he has nothing to lose and no time to waste.

To continue reading Michael Goodwin's column in the New York Post, click here.

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Michael Goodwin is a Fox News contributor and New York Post columnist.