Of course, the “Stand With Rand” placards that greeted the Kentucky senator last week at the Conservative Political Action Conference, the Rubio accolades and the attention showered on his affinity for rap and his abrupt lurch for water during his State of the Union response — all of that might be froth that bubbles away when the next Republican beauty contestants appear.

Dave Funk, who just stepped down as chairman of the Republican Party of Polk County, Iowa, home to Des Moines, said he was not sure the real 2016 contenders had even appeared on the radar. “Most of us are looking at these guys and saying, ‘Why don’t you go back to the work we pay you to do and impress us by getting something exceptional done, not coming out here to tell us how wonderful you are?’ ” he said.

But for better or worse, Senators Rubio and Paul have come to represent this moment’s fork in the Republican road. Mr. Rubio, who divided the Republican establishment in 2010 with his brash primary challenge to former Gov. Charlie Crist’s Senate run in Florida, looks like the establishment’s man for now.