MIAMI — Republican Sen. Marco Rubio is getting help from an unlikely quarter as he campaigns for re-election: the Democratic Party.

The party’s Senate committee this week abandoned Rubio’s rival, congressman Patrick Murphy, yanking advertising off the expensive airwaves of the Sunshine State and sending the money to competitive races in smaller states where fundraising dollars go further.

The decision leaves Murphy largely on his own. He has raised only about one-third as much as Rubio in recent months.

And the decision has prompted a round of second-guessing from Democrats who argue that Rubio is beatable and the party should not be helping him win a second term that could provide a perch for another presidential bid.