MADISON, Wis. (AP) — Scott Walker has downshifted his initially ambitious campaign for president to focus on first-to-vote Iowa, scrambling Thursday to reassure jittery donors and supporters after a quiet performance in the second Republican debate.

Walker spoke less than anyone else during a three-hour marathon in which he was asked only two direct questions. While Walker's campaign manager said on Twitter it was "ridiculous" how little attention his boss got from the debate's moderators, Walker said afterward it was time to adjust his strategy to win the Republican nomination.

"We're putting all our eggs in the basket of Iowa," he told MSNBC.

But first, Walker needs to settle donors hedging their bets on the Wisconsin governor. Among them is billionaire media mogul Stanley Hubbard, who said Thursday that while he still supports Walker, he's going to also start giving money to Carly Fiorina, Marco Rubio and Chris Christie.

"For some reason, the people I'm close to, they aren't getting excited about him," said Hubbard, who gave $100,000 to two pro-Walker groups earlier this year. "And I don't know why. He's saying the right things."

The turnabout comes a few days after Walker, seeking to spark a campaign that has lagged in polls and fundraising after a fast start, unveiled a sweeping proposal to reshape organized labor in the United States. Designed to be a dramatic moment on Walker's signature issue, he wasn't asked about it during Wednesday's debate and he didn't bring it up on his own.

Walker and campaign manager Rick Wiley told donors on a conference call Thursday afternoon that he retains key strengths in Iowa. His favorability ratings in a recent statewide poll were higher than nearly anyone else, and he has campaign leaders in each of the state's 99 counties, a level of organization that should pay off in the February caucuses.

Walker returns to the state this weekend for a speech at an Iowa Faith & Freedom Coalition dinner in Des Moines on Saturday night, followed by a full day of campaigning Sunday.

"The biggest thing for us is getting back to the basics, getting into Iowa and the early states," Walker told MSNBC after the debate.

One of Walker's top fundraisers, Chicago Cubs co-owner Todd Ricketts, praised Wiley during the conference call in an effort to quell grumbles from some donors that the campaign needs a change.

Some of the campaign's top donors and fundraisers have expressed worry in recent weeks, as Walker's poll numbers have slipped, that he'll close out his first three months of fundraising without having raised enough to run a competitive campaign. Walker joined the call Thursday to personally plead for money.

Nervous campaign vendors are currently waiting to be paid more than $100,000 for outstanding debts, according to a person at one of the firms who spoke on the condition of anonymity. The person was not authorized to speak publicly about the firm's financial relationship to Walker's campaign.

The person said there is widespread recognition that Walker built a large and expensive campaign infrastructure when fundraising appeared strong earlier in the year. That is leading to fears among Walker's creditors that he could become this cycle's Tim Pawlenty, the former Minnesota governor who left the 2012 presidential race deep in debt months before the first votes were cast.

In addition to Thursday's 30-minute conference call, Walker courted donors directly in California. He has a series of fundraisers planned, including next week in New York City and later this month in his home state.

Walker still benefits from two outside groups that can raise unlimited amounts of money from donors, and they reported amassing $26 million in the first six months of the year, before Walker made his candidacy official.

But like Hubbard, some of Walker's biggest financial supporters have spread their largesse from the start, an indication that they're not committed to him for the long haul.

Robert McNair, the billionaire owner of the Houston Texans, gave $500,000 to a pro-Walker super PAC — and the same amount to groups backing Jeb Bush, Ted Cruz and Lindsey Graham. Chicago billionaire hedge-fund manager Ken Griffin cut $100,000 checks this spring to Walker, Rubio and Bush.

That's a smart strategy for donors, Hubbard said Thursday.

"I'm not going to turn my back on Walker," he said. "I'm still continuing to back him. ... But I think it's good to have a robust team."

Walker still has a path to victory in Iowa, but interest has moved away from him and toward Fiorina, Donald Trump and Ben Carson, said Will Rogers, chairman of the Republican Party in Iowa's Polk County.

"I don't think people disqualify Scott Walker. I think they still look at him and respect him. I think that at the same time, the attention has really shifted from someone like Scott Walker, it has really shined on (Donald) Trump," Rogers said.

But Roger Pilc, a Connecticut technology executive involved in an upcoming New York fundraiser for Walker, said he expects interest in the governor to increase as other candidates fade away.

"He'll rise back up," Pilc predicted, "as he shows that he is an outsider to Washington, but one who has a record of getting things done."

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Bykowicz reported from Washington. Associated Press writers Steve Peoples in Simi Valley, California, and Catherine Lucey in Des Moines contributed to this report.

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