Unaffiliated political strategists, operatives from rival campaigns, and Walker allies — almost all of whom requested anonymity to speak frankly — describe a number of challenges and mistakes. Walker’s rise came so early that he didn’t yet have a campaign in place and hadn’t fully studied up on national issues, and it showed. His Iowa bounce played into a key strategic decision to make the Hawkeye State central to his campaign, and relatedly, to compete directly for the Right of the party, which for him required changes in tone and position. Walker is a conservative but not a fire-breather. That made his attempt to straddle the grassroots and the establishment — which would have been difficult for any politician — harder to pull off.

Above all, the past few months have amplified questions about whether Walker’s campaign and, more importantly, the candidate himself are built to thrive on a stage larger and less forgiving than Wisconsin. Political observers had long worried about whether he had the charisma to succeed in a presidential contest. Now, there are doubts about his substance. At times, the candidate and his operation have appeared accident-prone and politically immature…

“He made a strategic error that’s fairly fundamental,” argues a strategist for one rival candidate. “What happened to Walker is that he started off fairly well-positioned, with a good story to tell about his record in Wisconsin, but he moved very far to the right, where he ran into other candidates who were more appealing to that audience. . . . He didn’t look like the best guy to that audience in comparison to those alternatives, and by making that move he abandoned the center of the Republican electorate, so now he’s left with neither the center nor the right.”