BOSTON – Keeping his secrets, Mitt Romney tends to lift the veil on his finances and campaign only if the law says he must.

The Republican presidential candidate refuses to identify his biggest donors who "bundle" money for his campaign. He often declines to say who's meeting with him or what he's doing for hours at a time. He puts limits on media access to his fundraisers. And he resists releasing all of his tax returns, making just a single year public after facing pressure to do so.

"We've released all the information required by law and then some," Romney said last month about his tax returns.