“It’s the shiny object principle. He wants to be first, get in the conversation...”

Mr. Cruz and his advisers, recalling his path to victory in Texas, saw more opportunity than risk in dispensing with any exploratory phase: In 2012, Mr. Cruz entered what was initially a crowded Republican field more than a year before the Senate primary and slowly earned support from conservative activists through intensive travel and on the strength — and uncompromising nature — of his rhetoric.

He now plans on pursuing a similar presidential campaign, portraying himself as not only the most doctrinaire candidate, but as the one most willing to fight for the principles of the conservative movement.

Kellyanne Conway, a Republican pollster, said that distinction could help Mr. Cruz win over the party’s hard-line activists.

“It’s not necessary for him to show that he’s the most conservative, but that he’s the most courageous conservative,” she said.