WASHINGTON (Reuters) - Republican presidential candidate Rick Santorum released tax returns on Wednesday showing he and his wife earned around $1 million annually in the last few years, Politico reported.

Santorum issued returns for the last four years, the most of the Republican candidates who have tried to outdo each other in showing transparency about their taxes.

The former Pennsylvania senator and his wife earned $659,000 in 2007, $952,000 in 2008, $1.1 million in 2009 and about $923,000 in 2010, the newspaper said.

They paid about $167,000 in taxes in 2007, some $262,000 in 2008, $310,000 in 2009, and $263,000 in 2010.

Former private equity executive Mitt Romney, by far the richest man in the 2012 White House race, released tax records in January indicating he will pay $6.2 million in taxes on a total of $42.5 million in income over the years 2010 and 2011.

Rival Newt Gingrich earlier revealed that he and his wife Callista paid $995,000 on an income of $3.1 million in 2010.

(Reporting By Alistair Bell; Editing by Doina Chiacu)