Gov. Scott Walker of Wisconsin has concluded he no longer has a path to the Republican presidential nomination and plans to drop out of the 2016 campaign, according to three Republicans familiar with his decision, who spoke on condition of anonymity.

Mr. Walker called a news conference in Madison at 6 p.m. Eastern time.

“The short answer is money,” said a supporter of Mr. Walker’s who was briefed on the decision. “He’s made a decision not to limp into Iowa.”