A former senior adviser to Donald Trump claims the Republican presidential front-runner has virtually no campaign infrastructure in the primary states that lie ahead.

Roger Stone, who left the Trump campaign last August, said Wednesday on Breitbart News radio that the billionaire should consider his landslide loss in Wisconsin a warning to his campaign that it needs to be better organized in states like Pennsylvania, Maryland and Indiana, which are set to hold their nominating contests between now and early May.

"It's an early wakeup call, as it were, for the Trump campaign," Stone said.

He continued, "Look, Trump's campaign has been fueled, from the beginning, with these hot button issues and an extraordinary communications-based strategy, where you utilize these huge rallies, the incredible media coverage they have generated, plus the high-profile debates, plus — give Trump credit — any interview he could do, as many interviews as he could do to reach as many voters he can reach."

"That has worked. Up until now," Stone suggested.

According to the Trump loyalist, the same woman who ran Trump's campaign operation in Wisconsin "previously ran Oklahoma for Trump" and had zero experience running any type of political campaign.

"This is something I see again and again, particularly at the ground roots level," he said, adding, "I salute these people for their enthusiasm, but this is a science. This is not something we guess about."

Stone continued, this time mentioning states that have already begun, or will soon begin to elect the delegates they'll send to the Republican National Convention in July.

"Now you move to a series of states like Colorado, Wyoming, and Arizona [which] should be watched very carefully. Those become hand-to-hand combat at state conventions or state committee meetings, where once again the Trump people have built no infrastructure," he said.

Stone compared the Trump campaign's lack of organization to the difficulties Ronald Reagan encountered during his failed White House bid in 1976.

"The Trump people are playing catch-up ball. They have to still worry about New Jersey, New York, Delaware and Pennsylvania, some big states going forward which are winner-take-most," he said.

Adding, "We also have to wonder, what is the psychological impact of Trump's support in those states now that he has lost a stand-alone primary and lost it by double digits."