Trump posts photo signing 'recent tax return'
© Greg Nash

Republican presidential front-runner Donald TrumpDonald John TrumpKoch-backed group launches six-figure ad buy against Heitkamp Anti-abortion Dem wins primary fight Lipinski holds slim lead in tough Illinois primary fight MORE on Thursday tweeted a photo that he says shows him signing a "recent tax return."

The photo appears to be identical to one he posted on Twitter in October:

2012 Republican presidential nominee Mitt Romney on Wednesday said Trump has not yet released his tax returns because there is a "bombshell" in the documents.

"I think there's something there," Romney said on Fox News. "Either he's not anywhere near as wealthy as he says he is, or he hasn't been paying the kind of taxes we whould expect him to pay, or perhaps he hasn't been giving money to the vets or to the disabled like he's been telling us he's doing."

Trump said Wednesday he was "in no rush" to release his returns.