State Treasurer
In May 2009, Mandel announced his candidacy for Ohio Treasurer of State via web video. Mandel's campaign generated controversy in late September 2010 when it ran a TV commercial falsely suggesting that Mandel's opponent, African-American Kevin Boyce, was a Muslim. The commercial was criticized for playing on anti-Muslim bias, and was ultimately withdrawn by the Mandel campaign. However, voters subsequently received a campaign mailing with similar themes. The Mandel campaign said that the Ohio Republican Party was responsible for the mailers, which had already been sent via bulk mail. In October 2010, in response to an Ohio Democratic Party complaint, the Ohio Elections Commission found that Mandel had deceptively depicted Boyce (an African Methodist Episcopal) as a Muslim in the ads.
On November 2, 2010, Mandel was elected Ohio State Treasurer, defeating Boyce by 14 percentage points to become chief investment officer of state funds. Mandel was sworn in on January 10, 2011.
During Mandel's time as treasurer, Ohio retained the highest possible rating from Standard & Poor's for the state's $4 billion government investment fund. On March 19, 2012, Mandel severed contracts with two major banks that handled $41 billion in Ohio pension investments, amid government investigations into whether the banks overcharged clients for currency trading, accusing them of "systematically exploiting public pension funds and taxpayers".
Mandel was reelected to a second term as state treasurer in 2014, defeating Democratic state representative Connie Pillich.
In December 2014, Mandel launched OhioCheckbook.com, a website that reports every expenditure in state government, in an effort, according to Mandel, to "create an army of citizen watchdogs who have the power to hold politicians accountable". Because there was no coordination with a similar effort undertaken by then-Governor John Kasich, Ohio ran two overlapping disclosure sites for several years. In June 2020, the state of Ohio merged the two sites, saving nearly a million dollars.
In summer 2015, Ohio passed legislation granting the Ohio Treasurer's Office the authority to open and administer ABLE accounts; such accounts are a federally authorized, state-run savings program for eligible people with disabilities. In June 2016, Mandel began offering the nation's first ABLE accounts, called in Ohio "STABLE Accounts". The Ohio Treasurer's Office, in addition to administering Ohio's STABLE Accounts, also jointly administers the ABLE accounts in Arizona, Georgia, Kentucky, Missouri, New Hampshire, New Mexico, Oklahoma, South Carolina, Vermont, West Virginia and Wyoming.
In 2016 and 2017, the Ohio Treasurer's Office under Mandel spent almost $1.7 million in taxpayer-funded television ads, featuring him and Urban Meyer, the head coach for the Ohio State Buckeyes football team. Mandel's office made each payment for the ads to individual television stations in an amount less than $50,000 per fiscal year, thus circumventing the need for approval by the state controlling board, which must sign off on state payments over this amount. Thirteen ad buys were within $1,000 of the $50,000 threshold. Mandel defended the ads, saying they helped increase awareness of an investment program for disabled Ohioans. Critics questioned the airing of self-promotional ads at a time when Mandel was running for U.S. Senate and said that Mandel's office was trying to avoid scrutiny by structuring the ad buys to avoid Controlling Board approval.
In response to the controversy, the Ohio House introduced an amendment to the state's 2017 budget. The amendment would require approval by the Controlling Board for ad buys that in aggregate exceed $50,000. This rule would have prevented Mandel from avoiding oversight by distributing the advertising campaign among individual ad buys. Mandel did not attend an Ohio Senate hearing on the matter. He sent a deputy instead.
In November 2018, Mandel made Ohio the first U.S. state to allow taxpayers to pay taxes with cryptocurrency. Mandel's initiative, OhioCrypto.com, allowed Ohio taxpayers to pay tax bills in Bitcoin; he described the initiative as a way to project Ohio as a state that is embracing blockchain technology. Mandel described himself as a cryptocurrency enthusiast and said that he hoped the launch of OhioCrypto.com would bring more legitimacy to cryptocurrency. Ohio Attorney General Yost subsequently found "The Treasurer's use of a payment processor to convert cryptocurrency into dollars for the payment of taxes is not authorized, expressly or impliedly, by statutes allowing the receipt of electronic payments." Mandel's successor suspended the program, noting that it had processed fewer than ten transactions.
