Bloomberg news, and the DNC, are piling on to Mitt Romney and Paul Ryan over GOP candidates’ reluctance to provide any details of their proposed $5 trillion tax cut for the rich.

Romney and Ryan have both repeatedly claimed that the tax cut will be paid for by closing “loopholes” and removed deductions. But they won’t say which loopholes and which deductions, nor will they promise not to eliminate the home mortgage interest deduction that so many Americans rely on.

During the vice presidential debate, both ABC’s Martha Radditz and VP Joe Biden couldn’t get Paul Ryan to say whether the home mortgage deduction was safe. That’s because it’s not.

RADDATZ: Can you declare anything off-limits? RYAN: Yeah, we’re saying close loopholes… RADDATZ: Home mortgage deduction? RYAN: … on high-interest people. RADDATZ: Home mortgage deduction? RYAN: For higher-income people. Here… BIDEN: Can you guarantee that no one making less than $100,000 will have a mortgage — their mortgage deduction impacted? Guarantee? RYAN: This taxes a million small businesses. He keeps trying to make you think that it’s just some movie star or hedge fund guy or an actor…

It’s not surprise that Ryan and Romney don’t want to talk about the details of their tax plan, because the non-partisan Tax Policy Center determined that the plan is “mathematically impossible.” While Romney and Ryan point to “six studies” that prove their plan will work. Except that the six studies aren’t really studies and they don’t prove anything. Even Fox News was incredulous over the lack of any proof that this tax cut can work:

It seems that Ryan and Romney don’t have the details because there aren’t any. Mitt Romney has both claimed that the $5 trillion tax cut will cut taxes for everyone AND not cut taxes for the wealthy. So which is it? No one has a clue because Romney has claimed both things to be true.

Romney talking about his $5 trillion tax cut in one debate: “Cut taxes for the rich? That’s not what I’m gonna do.” Romney talking about his $5 trillion tax cut in another debate: “We’re gonna cut taxes on everyone across the country by 20%, including the top one percent.”

Bloomberg reminds us that George Bush’s tax cuts were going to help focus on the middle class and pay for themselves. In fact, they did the opposite:

The desire for specificity is hardly unreasonable. Running in 2000, George W. Bush insisted that his proposed tax cut would be a boon to the middle class. Experts demurred, arguing that the top 1 percent of income earners would reap a windfall. Like Romney, Bush declined to show his math. In the end, his 2001 tax cut delivered almost half of its benefits to the top 1 percent and initiated Bush’s march toward a trillion-dollar deficit.

Maybe the details of Romney’s tax cut are hiding with his tax returns. And Jimmy Hoffa.