PROVIDENCE, R.I. (AP) — A Democratic gubernatorial candidate in Rhode Island issued a cease-and-desist letter Tuesday to the incumbent governor over an advertisement he says is defamatory.

An attorney for Matt Brown's campaign issued the letter to Democratic Gov. Gina Raimondo's campaign. The letter demands the Raimondo campaign issue a retraction and stop making "false and defamatory statements."

The Raimondo campaign stood by the ad, calling the letter a "last-gasp stunt by a failed candidate."

In the ad, Raimondo's campaign accuses Brown of "apparent laundering of campaign contributions," hiding his debt and not paying campaign workers during a failed bid for the U.S. Senate. Brown ran for Senate in 2006 but dropped out following a campaign-finance scandal.

Brown was accused of trying to circumvent contribution limits by taking $25,000 from Democratic parties in three other states, then steering top donors who had maxed out to give money to those parties. Brown denied wrongdoing but gave the money back. The Federal Election Commission later ruled the state parties did not break campaign-finance laws.

The cease-and-desist letter states that there was no criminal case and no allegation, let alone a finding, of money laundering. It says Brown's Senate campaign reported its debt to the FEC and paid the workers in full. Business vendors settled for half of what was owed under a plan the FEC approved, the letter says.

Brown's campaign is asking local television networks to stop running the ad.

"Rhode Islanders are smart and won't be fooled, and they won't let our democracy be bought by someone who lies and spends millions of dollars to trick voters and buy an election while refusing to do even one debate," Brown said in a statement Tuesday.

Raimondo so far has declined to participate in the typical debates leading up to the Sept. 12 primary.

Raimondo campaign spokeswoman Emily Samsel said the ad informing Rhode Islanders about Brown's "history of fiscal mismanagement is straightforward and factual" and the campaign will keep airing its ads as planned.

Also Tuesday, Republican candidate Patricia Morgan said as governor, she would root out government waste with the help of another former gubernatorial contender, Ken Block. Block has offered to do a free study of the state's temporary disability insurance program to look for waste and fraud, Morgan said. Block is the president of Simpatico Software Systems. He ran for governor in 2014, but was defeated in the Republican primary by Cranston Mayor Allan Fung, Morgan's opponent this year.

The Providence Journal reports Simpatico is one of two companies that's currently accusing the state of mishandling the bidding process as it looks to buy a data-mining computer system for detecting waste and fraud across government agencies.