Mr. West, a Republican positioned near the top of the Democrats’ knockout list, is fond of letting words speak for themselves — no parsing, no apologizing, no backtracking. In this era of survey-tested language, he is a verbal street brawler, unflinching in his speech, a trait that has won him the adulation (and the campaign contributions) of conservatives and Tea Party supporters who cheer on his every Westism. He is one of the top fund-raisers among House Republicans, rivaling Speaker John A. Boehner. …

Despite his celebrity and prodigious fund-raising, Mr. West, who announced he would run in a new district this year, faces a serious challenge in November. The question for Democrats is this: Will Mr. West’s conservative stance and unbridled style pass muster with a new set of Florida voters in a swing district that is evenly split? In that race, Mr. West is likely to face Patrick Murphy, 30, a Democrat and political neophyte who is shaping up to be a potent force.

Democrats are banking that in a presidential election year, Mr. West will fail to sway enough independent-minded voters to win in November. They view the newly created 18th Congressional District on the Treasure Coast as one of six possible Democratic gains in Florida. Impressed with Mr. Murphy’s fund-raising, the Democratic Congressional Campaign Committee has put its financial and organizational strength behind him.