His long-promised “next phase” defined by new spending, such as a wave of television commercials, has so far failed to materialize, week after week. His advisers have not revealed the existence of any pollsters on their staff or any advertising team. He has no real research operation to examine his own vulnerabilities or those of his opponents and, based on Federal Election Commission filings, little in the way of a voter contact operation to identify and turn out his supporters…

Mr. Robinson said Mr. Trump had hurt himself in Iowa by not augmenting his news presence with a parallel effort to push his message through ads, mailers and phone banks. “Such an effort would have also inoculated him from attack,” he said.

If Mr. Trump’s team had researched Mr. Cruz’s weaknesses, for example, then incorporated them in Mr. Trump’s heavily covered speeches and ceaseless television appearances, as well as in paid advertising, he may have been able to pre-empt or at least slow the senator’s rise there. Mr. Trump does not appear to have used a pollster to target his message or identify pockets of support, except for one survey early on.

“While leading in the polls for months and not spending any real money on advertising is novel, the Trump team needs to turn on the spending for a real advertising and turnout operation or prepare to lose Iowa and New Hampshire,” said Scott Reed, the top political strategist for the U.S. Chamber of Commerce.