President Trump has been pushing Rick Scott to run for Senate, and on Monday he got his wish. The Florida governor will challenge Sen. Bill Nelson for the seat the Democrat has held since 2001, one that's considered particularly vulnerable. The AP reports Nelson is Florida's only statewide-elected Democrat, and it notes that term limits prevent Scott from making another run for governor. The consensus is that the race will be a standout of the midterms: a likely highly expensive "epic battle," as Politico puts it, and one that will test "the limits of whether a close alliance with ... Trump is political poison or a pathway to success in the nation's biggest swing state."
As for why Nelson's seat is considered more up for grabs than most, NBC News points to Charlie Cook of the Cook Political Report, who gave Nelson the top slot on his "most vulnerable" Democrats list—and explained the seat is so shaky because of Scott. "Florida is among the most-purple, most-competitive states in the country, and Scott would have the personal financial resources to run a first-class campaign even without raising money from others," Cook wrote in January. "Should Scott decide not to run, Nelson would instantly become a strong, if not prohibitive favorite, but I don't think this will happen." At the National Review, John Fund reports recent polls show Nelson just four points over Scott, "but Scott has overcome much bigger deficits in the past," he writes. The AP has more on Scott's political record and how the candidates will likely go after each other here.