Still, the 2016 field is wide open on the GOP side — and even some Republican governors looking at a White House run lack hefty résumés themselves. The three senators’ efforts to position themselves suggest that each is, in essence, asking to be judged mainly on the strength of his ideas — not strictly on whether he has enough experience for the job.

Rubio, 42, has been globetrotting to beef up his foreign policy credentials while methodically rolling out domestic proposals on topics ranging from battling poverty to overhauling retirement programs, an issue he will discuss Tuesday at the National Press Club.

Paul, 51, has been traveling across the nation, trying to showcase his appeal beyond conservative base voters by pushing economic policy measures he says will appeal to a diverse array of Americans, including young people and those in inner cities who typically lean Democrat.

And Cruz, 43, is trying to show that he has been spearheading the right’s fight in his 15 months in Washington, whether it’s on Obamacare, the deficit or Benghazi. That sort of leadership, the senator says, is what voters will be looking for in the next presidential election.