( CNN) Marco Rubio is back in the thick of it.

The Florida Republican, who reversed his decision to quit the Senate after his losing the GOP presidential nomination, abruptly determines himself at the center of the political intrigue swirling around Donald Trump’s nascent administration.

Rubio’s tough questioning Wednesday of Rex Tillerson, Trump’s pick for secretary of state, and unresolved doubts concerning the former ExxonMobil chief’s nomination, present him with a set of provocative political choices.

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