Leading presidential hopeful and former U.S. House Speaker Newt Gingrich released tax returns late Thursday showing he and his wife Callista earned $3.14 million in 2010.

The tax returns showed the couple paid $994,708 or 31.6 percent of their income, in taxes. By contrast, GOP frontrunner Mitt Romney said earlier this week that he pays about 15 percent in taxes on his multi-million-dollar income.

Gingrich has pushed Romney to release his returns, saying he should do so before Republicans pick a nominee. Romney said Thursday night he will release multiple years of tax returns when this year's returns are completed.

The couple's returns showed the Gingriches donated about $81,000 to charity in 2010, or about 2.5 percent of his income.

The returns showed Gingrich paid $19,800 in alimony. Newt Gingrich has two ex-wives.

Most of the income the couple reported came from partnerships and S corporations, including Gingrich Holdings. Mrs. Gingrich reported earning about $197,000, mostly from Gingrich Productions, which peddles Gingrich's books and other materials.

The former speaker also reported getting a Congressional pension of $76,200.

The returns showed the couple paid a $1,543 tax penalty and spent $8,505 for tax preparation.

Gingrich also released taxes for his charitable Gingrich Foundation, which donated money to several charities, including three Atlanta-area schools and the Atlanta Ballet.