Mitt Romney, a multimillionaire who is by far the wealthiest of the Republican presidential candidates, said he has no plans to release his income tax returns if he wins his party’s nomination, setting himself apart from past nominees in both parties who have routinely done so.

Romney, whose most recent disclosure in August estimated his personal wealth at as much as $250 million, said Dec. 22 he had already released extensive financial information and had no “current plans” to make his tax returns public.

If the former Massachusetts governor wins the nomination and sticks to his plan, he would be one of the only presidential nominees in the last three decades to withhold his income tax return. While income tax information is private and there is no legal obligation to disclose it, presidents and nominees for the office have regularly done so since the 1970s.