Story highlights The Clinton campaign is launching a new TV ad

It focuses on Trump's failure to release his tax returns

New York (CNN) Hillary Clinton's campaign is putting money behind their new chosen attack on Donald Trump.

Clinton's campaign will begin airing a new ad -- titled "Absolutely" -- on Thursday that hits Trump for not releasing his tax returns despite saying in 2014 that he "absolutely" would in a interview with an Irish television station.

Clinton and her top aides have tried to weaponize Trump's lack of disclosure on taxes, repeatedly slamming the Republican nominee and speculating why he is declining to do what decades of presidential nominees have done.

"Under his plans, Donald Trump would pay lower tax rate than middle class families," Clinton said Wednesday in Cleveland. "Of course, we have no idea what tax rate he pays because unlike everybody else who has run for president he refuses to release his tax returns so American people can't really judge."

Clinton's use of Trump's tax returns are an effort to raise credibility and honesty questions around the Republican nominee, an effort that Clinton's top aides hope will leave voters questioning whether Trump either has ties to questionable businesses or isn't as wealthy as he says he is.

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