washington former republican presidential candidate marco rubio seek re-election u.s. senate seat announce wednesday reverse pledge run say prospect donald trump presidency worry first-term florida senator say senate frustrate also place policy advance make one counteract power white house begin next chapter history nation another role senate could end important years come constitutional power act check balance excesses president rubio say statement 45-year-old lawmaker prove fund-raiser well know nationally intense pressure run especially give cost contest important election swing-state campaign advertise expensive republicans likely retain seat candidate nov. general election face tough fight preserve majority senate could also rally republican voters head poll state critical presidential race president barack obama democrat take florida one percentage-point margin 2012 republican mitt romney year republicans must defend 24 54 seat hold 100-member senate compare 10 democrats fight retain senate majority leader mitch mcconnell say would terrific outcome rubio decide run rubio harsh word hillary clinton presumptive democratic presidential nominee predict election would mean four years term obama fail policies say prospect republican presidential candidate donald trump win white house also worrisome cite trump statements women minorities note many likely republican nominee position important issue unknown elect need senators will encourage right direction necessary stand rubio statement say still pledge vote trump real estate mogul political neophyte shake republican establishment choice want ... choice lot people comfortable choice tell cnn interview announcement mention massacre last week gay nightclub orlando florida say recent days reconsider decision run concern serious events country include mass shoot decision reverse campaign pledge rubio make year ago retire senate presidential bid fail end bid nomination march lose primary home state trump follow harsh war word cook political report say rubio announcement breathe new life republican chance hold onto seat still rat race toss-up cite poor senate attendance record senator remark presidential campaign frustrate upper chamber republican u.s. representative david jolly seek senate seat open door rubio run step aside last week wednesday announcement florida lieutenant governor carlos lopez cantera friend rubio republican u.s. representative ron desantis also scrap plan seek seat republicans however announce plan quit ahead florida aug. 30 primary u.s. representative patrick murphy lead democratic challenger accuse rubio first abandon constituents treat like consolation prize rubio seek re-election senate say trump 'worrisome