Former Massachusetts Gov. Mitt Romney is challenging Florida Gov. Charlie Crist to either stay in the U.S. Senate race as a Republican or step aside and support his opponent.
Romney's comments came at a Tampa rally Monday where he officially endorsed GOP challenger Marco Rubio. Romney said he expects "Crist to do the right thing."
There is speculation that Crist might bolt the Republican Party and run as an independent.
Recent polls show Crist is well behind Rubio in the Republican primary but could win a three-way general election race against Rubio and the likely Democratic nominee, U.S. Rep. Kendrick Meek.
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