WASHINGTON — Jeb Bush is one of the country's most visible advocates of Common Core, forcefully defending the K-12 standards even as it puts him at odds with a conservative base he would need to mount a viable campaign for president.

But his problem is deeper than policy.

Bush's Foundation for Excellence in Education has collected millions of dollars from pro-Common Core organizations — from the Bill and Melinda Gates Foundation to the for-profit education giant Pearson — giving critics something to sink into and drawing attention to the venture that has allowed the former Republican governor to expand his profile beyond Florida.

The ties fuel detractors who assert the standards are being pushed by big business interests, such as the company whose CEO sits on the Bush foundation board.

"When it comes to Common Core peddlers like @JebBush et al: Don't read their lips. Follow the money," commentator Michelle Malkin tweeted in March to her 707,000 followers.

Questions have surfaced in grass roots conservative and tea party circles as well as on websites for Glenn Beck and FreedomWorks, where a post reads, "Jeb Bush and the Common Core Money Trail."

These same sources have kindled opposition to Common Core as a policy, a movement that has gained a foothold. (You've got a problem when Stephen Colbert mocks the complexity of math problems.) Some critics on the left also have attacked the standards being implemented in more than 40 states.

"It's been a huge financial and political jackpot for Bush," Malkin said in an interview. "Advocating for purported high standards takes him across the country and puts him in touch with a lot of deep pockets. But, of course, he didn't anticipate this backlash. Does he still come out ahead by fronting for Common Core?"

That's a question that could be answered in the coming months as Bush, 61, reaches a decision on whether to run for president in 2016.

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Bush has gotten a lot of notice as a potential candidate, but Common Core has blossomed as a significant hurdle. Other Republican presidential hopefuls have distanced themselves from the standards, isolating Bush. Louisiana Gov. Bobby Jindal had been a Common Core supporter but this month compared it to "centralized planning" in Russia.

Bush, who formed the foundation in 2008 and does not take a salary, declined to be interviewed. His backers say questions about motives fly in the face of a focus on higher standards and testing that far predates Common Core.

"Gov. Bush has spent over 20 years as a passionate advocate for education reform including high standards, strong accountability, quality teachers and leaders, and school choice," foundation spokeswoman Jaryn Emhof said.

"In Florida since the A+ Plan was passed and implemented in 1999, Florida has reversed a generation of decline in education," she added. "Today, more students are graduating high school, participation and passing rates for Advanced Placement courses have improved and more third-grade students are reading at or above grade level, with minority students making the greatest gains."

She said individuals and organizations that support the foundation "do so because they support our agenda, not the other way around. Gov. Bush's record on education is clear, consistent and in the best interests of students."

This is not the first time the foundation, which raised nearly $10 million in 2012, has faced questions of advancing interests of donors.

Last year, a nonprofit group released scores of emails it received in public records requests from several states that, it said, showed foundation staff helped with legislation that could benefit for-profit foundation supporters. "It certainly is not surprising that In the Public Interest, a union-backed organization, opposes school choice and the expansion of digital education," Emhof said at the time, adding that the foundation "openly offers its expertise to legislators and policy makers interested in improving their education systems."

Some of the same foundation supporters that came under scrutiny have an interest in Common Core, including Pearson, the world's largest education company, and Amplify, a division of Rupert Murdoch's News Corp. Amplify's CEO, former New York City schools chancellor Joel Klein, sits on the Bush foundation board.

Last month, Pearson landed a lucrative contract with a consortium developing tests aligned with Common Core. Amplify last year won a $12.5 million contract from another Common Core consortium. It also has developed a tablet that comes with Common Core-aligned material.

The potential market for all the new materials required by Common Core is as much as $8 billion, according to the conservative Thomas B. Fordham Institute, which has partnered with the Bush foundation to promote the standards.

Other foundation backers with an interest in Common Core include publishers McGraw-Hill and Houghton Mifflin Harcourt. Microsoft, another foundation sponsor, in March announced a partnership with Pearson to develop Common Core material.

The companies say there is no relationship between their support of the foundation and their business interests, other than a mutual support of quality education.

"We support high standards, everyone does," said Pearson spokeswoman Stacy Skelly, adding that Pearson supports a range of education foundations.

Amplify spokesman Justin Hamilton said, "The foundation has helped foster a robust conversation around improving classroom education in America and we're proud to support their work."

Other pro-Common Core supporters include:

• The Bill and Melinda Gates Foundation, which has pumped more than $150 million into organizations developing Common Core, has given at least $5.1 million to Bush's foundation, including $2 million in October 2013 "to support Common Core implementation," according to the Gates' website. That followed $1.5 million Gates gave in August 2013 for "general operating support."

• The GE Foundation gave a foundation offshoot — Chiefs for Change, a group of education officials — a nearly $3.2 million grant "to create a road map for successful implementation of the Common Core State Standards in key states, maintain community support and advocate for replication nationwide."

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Critics say Bush has benefited from the foundation by using it as a platform to burnish his credentials as an education expert, reformer and wonk. In recent years, he has been on an endless national road show, making key connections and gaining media exposure.

"He definitely has profited," said Laura Zorc, a mother of four in Vero Beach who founded Florida Parents Against Common Core. "If Common Core standards are proven bad — and they are bad — he's not going to have a chance in Hades for the 2016 election. That's why he's fighting so hard."

Zorc and her allies have had some success pushing the debate and getting Florida to tweak Common Core (and rename it the Florida Standards). But she said big money has helped drown out dissent. Bush's foundation has paid for TV and radio ads and used its network to shore up support. National ads funded by other groups have run on Fox News.

"It's not that I'm anti-Jeb Bush," said Zorc, who volunteered for him during his 2002 re-election campaign. "He did a lot of good things. I wanted to think Common Core was as good as he was saying, but then I started digging into the research."

Zorc and others see a contradiction between Bush's Common Core support and his long-standing advocacy of school choice. Bush does not view them as mutually exclusive and studies indicate that most children will remain in public schools, therefore it's important to push for higher standards.

Bush seems both surprised and aggravated by the pushback to Common Core, much of it owing to conspiracy theories about a federal government takeover.

The standards were developed with federal incentives but were created by governors, state school officials and education experts. They are guidelines of what children should learn; the actual curriculum is left to the states.

"The fight about Common Core is political," Bush said at an event in Washington last year. "Meanwhile, back at the ranch, we have huge swaths of the next generation of Americans that can't calculate math. They can't read. Their expectations in their own lives are way too low. And we're not going to be able to sustain this extraordinarily exceptional country unless we challenge every basic assumption on how we do things."

Part of the problem is that the Common Core brand has become "toxic," as former Arkansas Gov. Mike Huckabee recently said. Republican pollster John McLaughlin last month showed how among GOP primary voters, approval for Common Core jumped from 33 percent to 59 percent when it was described as "a set of standards in math and English which state what a child should know in both subjects by the end of each grade of school they complete."

Contact Alex Leary at aleary@tampabay.com.