In the four months since his Senate loss, Mr. O’Rourke, 46, has done little to demonstrate the kind of intensive preparation — building national political infrastructure, projecting a signature policy rationale for a candidacy — typically associated with a top-flight presidential campaign.

There has been no flirtation tour in Iowa, no trip to New Hampshire since his college years as an Ivy League rower. Mr. O’Rourke had no traditional campaign-in-waiting at the ready after the midterms — the sort of operation available to a more experienced holdout like former Vice President Joseph R. Biden Jr. or carefully built over months by first-time presidential candidates like Senators Elizabeth Warren, Cory Booker and Kamala Harris. ...

Is this the moment for a relatively untested white male in a party eager to elevate female and nonwhite voices in the quest to dethrone President Trump?