Presidential hopeful Marco Rubio. Photo: Gage Skidmore.

AP – Some Jeb Bush donors have been slow to swing behind Marco Rubio since Bush’s exit from the Republican presidential race this weekend, leaving other donors nervous that the mainstream GOP is running out of time to rally behind a single candidate.

Despite key commitments for Rubio from parts of Bush’s vast fundraising network, others seem exhausted and disillusioned by what they thought was Bush’s clear shot at the presidency, eclipsed by the rise and durability of the outsider Donald Trump.

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